Merge commit v3.13-rc1 into kbuild/misc

23 files changed, 10133 insertions, 0 deletions

diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
new file mode 100644
index 000000000000..baab8e5e7f66
--- /dev/null
+++ b/kernel/locking/Makefile
@@ -0,0 +1,25 @@
+
+obj-y += mutex.o semaphore.o rwsem.o lglock.o
+
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_lockdep.o = -pg
+CFLAGS_REMOVE_lockdep_proc.o = -pg
+CFLAGS_REMOVE_mutex-debug.o = -pg
+CFLAGS_REMOVE_rtmutex-debug.o = -pg
+endif
+
+obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o
+obj-$(CONFIG_LOCKDEP) += lockdep.o
+ifeq ($(CONFIG_PROC_FS),y)
+obj-$(CONFIG_LOCKDEP) += lockdep_proc.o
+endif
+obj-$(CONFIG_SMP) += spinlock.o
+obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
+obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
+obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
+obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
+obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
+obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem-xadd.o
+obj-$(CONFIG_PERCPU_RWSEM) += percpu-rwsem.o
diff --git a/kernel/locking/lglock.c b/kernel/locking/lglock.c
new file mode 100644
index 000000000000..86ae2aebf004
--- /dev/null
+++ b/kernel/locking/lglock.c
@@ -0,0 +1,89 @@
+/* See include/linux/lglock.h for description */
+#include <linux/module.h>
+#include <linux/lglock.h>
+#include <linux/cpu.h>
+#include <linux/string.h>
+
+/*
+ * Note there is no uninit, so lglocks cannot be defined in
+ * modules (but it's fine to use them from there)
+ * Could be added though, just undo lg_lock_init
+ */
+
+void lg_lock_init(struct lglock *lg, char *name)
+{
+        LOCKDEP_INIT_MAP(&lg->lock_dep_map, name, &lg->lock_key, 0);
+}
+EXPORT_SYMBOL(lg_lock_init);
+
+void lg_local_lock(struct lglock *lg)
+{
+        arch_spinlock_t *lock;
+
+        preempt_disable();
+        lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
+        lock = this_cpu_ptr(lg->lock);
+        arch_spin_lock(lock);
+}
+EXPORT_SYMBOL(lg_local_lock);
+
+void lg_local_unlock(struct lglock *lg)
+{
+        arch_spinlock_t *lock;
+
+        lock_release(&lg->lock_dep_map, 1, _RET_IP_);
+        lock = this_cpu_ptr(lg->lock);
+        arch_spin_unlock(lock);
+        preempt_enable();
+}
+EXPORT_SYMBOL(lg_local_unlock);
+
+void lg_local_lock_cpu(struct lglock *lg, int cpu)
+{
+        arch_spinlock_t *lock;
+
+        preempt_disable();
+        lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
+        lock = per_cpu_ptr(lg->lock, cpu);
+        arch_spin_lock(lock);
+}
+EXPORT_SYMBOL(lg_local_lock_cpu);
+
+void lg_local_unlock_cpu(struct lglock *lg, int cpu)
+{
+        arch_spinlock_t *lock;
+
+        lock_release(&lg->lock_dep_map, 1, _RET_IP_);
+        lock = per_cpu_ptr(lg->lock, cpu);
+        arch_spin_unlock(lock);
+        preempt_enable();
+}
+EXPORT_SYMBOL(lg_local_unlock_cpu);
+
+void lg_global_lock(struct lglock *lg)
+{
+        int i;
+
+        preempt_disable();
+        lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
+        for_each_possible_cpu(i) {
+                arch_spinlock_t *lock;
+                lock = per_cpu_ptr(lg->lock, i);
+                arch_spin_lock(lock);
+        }
+}
+EXPORT_SYMBOL(lg_global_lock);
+
+void lg_global_unlock(struct lglock *lg)
+{
+        int i;
+
+        lock_release(&lg->lock_dep_map, 1, _RET_IP_);
+        for_each_possible_cpu(i) {
+                arch_spinlock_t *lock;
+                lock = per_cpu_ptr(lg->lock, i);
+                arch_spin_unlock(lock);
+        }
+        preempt_enable();
+}
+EXPORT_SYMBOL(lg_global_unlock);
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
new file mode 100644
index 000000000000..576ba756a32d
--- /dev/null
+++ b/kernel/locking/lockdep.c
@@ -0,0 +1,4257 @@
+/*
+ * kernel/lockdep.c
+ *
+ * Runtime locking correctness validator
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ * this code maps all the lock dependencies as they occur in a live kernel
+ * and will warn about the following classes of locking bugs:
+ *
+ * - lock inversion scenarios
+ * - circular lock dependencies
+ * - hardirq/softirq safe/unsafe locking bugs
+ *
+ * Bugs are reported even if the current locking scenario does not cause
+ * any deadlock at this point.
+ *
+ * I.e. if anytime in the past two locks were taken in a different order,
+ * even if it happened for another task, even if those were different
+ * locks (but of the same class as this lock), this code will detect it.
+ *
+ * Thanks to Arjan van de Ven for coming up with the initial idea of
+ * mapping lock dependencies runtime.
+ */
+#define DISABLE_BRANCH_PROFILING
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/interrupt.h>
+#include <linux/stacktrace.h>
+#include <linux/debug_locks.h>
+#include <linux/irqflags.h>
+#include <linux/utsname.h>
+#include <linux/hash.h>
+#include <linux/ftrace.h>
+#include <linux/stringify.h>
+#include <linux/bitops.h>
+#include <linux/gfp.h>
+#include <linux/kmemcheck.h>
+
+#include <asm/sections.h>
+
+#include "lockdep_internals.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/lock.h>
+
+#ifdef CONFIG_PROVE_LOCKING
+int prove_locking = 1;
+module_param(prove_locking, int, 0644);
+#else
+#define prove_locking 0
+#endif
+
+#ifdef CONFIG_LOCK_STAT
+int lock_stat = 1;
+module_param(lock_stat, int, 0644);
+#else
+#define lock_stat 0
+#endif
+
+/*
+ * lockdep_lock: protects the lockdep graph, the hashes and the
+ *               class/list/hash allocators.
+ *
+ * This is one of the rare exceptions where it's justified
+ * to use a raw spinlock - we really dont want the spinlock
+ * code to recurse back into the lockdep code...
+ */
+static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+
+static int graph_lock(void)
+{
+        arch_spin_lock(&lockdep_lock);
+        /*
+         * Make sure that if another CPU detected a bug while
+         * walking the graph we dont change it (while the other
+         * CPU is busy printing out stuff with the graph lock
+         * dropped already)
+         */
+        if (!debug_locks) {
+                arch_spin_unlock(&lockdep_lock);
+                return 0;
+        }
+        /* prevent any recursions within lockdep from causing deadlocks */
+        current->lockdep_recursion++;
+        return 1;
+}
+
+static inline int graph_unlock(void)
+{
+        if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
+                /*
+                 * The lockdep graph lock isn't locked while we expect it to
+                 * be, we're confused now, bye!
+                 */
+                return DEBUG_LOCKS_WARN_ON(1);
+        }
+
+        current->lockdep_recursion--;
+        arch_spin_unlock(&lockdep_lock);
+        return 0;
+}
+
+/*
+ * Turn lock debugging off and return with 0 if it was off already,
+ * and also release the graph lock:
+ */
+static inline int debug_locks_off_graph_unlock(void)
+{
+        int ret = debug_locks_off();
+
+        arch_spin_unlock(&lockdep_lock);
+
+        return ret;
+}
+
+static int lockdep_initialized;
+
+unsigned long nr_list_entries;
+static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
+
+/*
+ * All data structures here are protected by the global debug_lock.
+ *
+ * Mutex key structs only get allocated, once during bootup, and never
+ * get freed - this significantly simplifies the debugging code.
+ */
+unsigned long nr_lock_classes;
+static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
+
+static inline struct lock_class *hlock_class(struct held_lock *hlock)
+{
+        if (!hlock->class_idx) {
+                /*
+                 * Someone passed in garbage, we give up.
+                 */
+                DEBUG_LOCKS_WARN_ON(1);
+                return NULL;
+        }
+        return lock_classes + hlock->class_idx - 1;
+}
+
+#ifdef CONFIG_LOCK_STAT
+static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
+                      cpu_lock_stats);
+
+static inline u64 lockstat_clock(void)
+{
+        return local_clock();
+}
+
+static int lock_point(unsigned long points[], unsigned long ip)
+{
+        int i;
+
+        for (i = 0; i < LOCKSTAT_POINTS; i++) {
+                if (points[i] == 0) {
+                        points[i] = ip;
+                        break;
+                }
+                if (points[i] == ip)
+                        break;
+        }
+
+        return i;
+}
+
+static void lock_time_inc(struct lock_time *lt, u64 time)
+{
+        if (time > lt->max)
+                lt->max = time;
+
+        if (time < lt->min || !lt->nr)
+                lt->min = time;
+
+        lt->total += time;
+        lt->nr++;
+}
+
+static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
+{
+        if (!src->nr)
+                return;
+
+        if (src->max > dst->max)
+                dst->max = src->max;
+
+        if (src->min < dst->min || !dst->nr)
+                dst->min = src->min;
+
+        dst->total += src->total;
+        dst->nr += src->nr;
+}
+
+struct lock_class_stats lock_stats(struct lock_class *class)
+{
+        struct lock_class_stats stats;
+        int cpu, i;
+
+        memset(&stats, 0, sizeof(struct lock_class_stats));
+        for_each_possible_cpu(cpu) {
+                struct lock_class_stats *pcs =
+                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
+
+                for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
+                        stats.contention_point[i] += pcs->contention_point[i];
+
+                for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
+                        stats.contending_point[i] += pcs->contending_point[i];
+
+                lock_time_add(&pcs->read_waittime, &stats.read_waittime);
+                lock_time_add(&pcs->write_waittime, &stats.write_waittime);
+
+                lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
+                lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
+
+                for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
+                        stats.bounces[i] += pcs->bounces[i];
+        }
+
+        return stats;
+}
+
+void clear_lock_stats(struct lock_class *class)
+{
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                struct lock_class_stats *cpu_stats =
+                        &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
+
+                memset(cpu_stats, 0, sizeof(struct lock_class_stats));
+        }
+        memset(class->contention_point, 0, sizeof(class->contention_point));
+        memset(class->contending_point, 0, sizeof(class->contending_point));
+}
+
+static struct lock_class_stats *get_lock_stats(struct lock_class *class)
+{
+        return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
+}
+
+static void put_lock_stats(struct lock_class_stats *stats)
+{
+        put_cpu_var(cpu_lock_stats);
+}
+
+static void lock_release_holdtime(struct held_lock *hlock)
+{
+        struct lock_class_stats *stats;
+        u64 holdtime;
+
+        if (!lock_stat)
+                return;
+
+        holdtime = lockstat_clock() - hlock->holdtime_stamp;
+
+        stats = get_lock_stats(hlock_class(hlock));
+        if (hlock->read)
+                lock_time_inc(&stats->read_holdtime, holdtime);
+        else
+                lock_time_inc(&stats->write_holdtime, holdtime);
+        put_lock_stats(stats);
+}
+#else
+static inline void lock_release_holdtime(struct held_lock *hlock)
+{
+}
+#endif
+
+/*
+ * We keep a global list of all lock classes. The list only grows,
+ * never shrinks. The list is only accessed with the lockdep
+ * spinlock lock held.
+ */
+LIST_HEAD(all_lock_classes);
+
+/*
+ * The lockdep classes are in a hash-table as well, for fast lookup:
+ */
+#define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
+#define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
+#define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
+#define classhashentry(key)     (classhash_table + __classhashfn((key)))
+
+static struct list_head classhash_table[CLASSHASH_SIZE];
+
+/*
+ * We put the lock dependency chains into a hash-table as well, to cache
+ * their existence:
+ */
+#define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
+#define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
+#define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
+#define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
+
+static struct list_head chainhash_table[CHAINHASH_SIZE];
+
+/*
+ * The hash key of the lock dependency chains is a hash itself too:
+ * it's a hash of all locks taken up to that lock, including that lock.
+ * It's a 64-bit hash, because it's important for the keys to be
+ * unique.
+ */
+#define iterate_chain_key(key1, key2) \
+        (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
+        ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
+        (key2))
+
+void lockdep_off(void)
+{
+        current->lockdep_recursion++;
+}
+EXPORT_SYMBOL(lockdep_off);
+
+void lockdep_on(void)
+{
+        current->lockdep_recursion--;
+}
+EXPORT_SYMBOL(lockdep_on);
+
+/*
+ * Debugging switches:
+ */
+
+#define VERBOSE                 0
+#define VERY_VERBOSE            0
+
+#if VERBOSE
+# define HARDIRQ_VERBOSE        1
+# define SOFTIRQ_VERBOSE        1
+# define RECLAIM_VERBOSE        1
+#else
+# define HARDIRQ_VERBOSE        0
+# define SOFTIRQ_VERBOSE        0
+# define RECLAIM_VERBOSE        0
+#endif
+
+#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
+/*
+ * Quick filtering for interesting events:
+ */
+static int class_filter(struct lock_class *class)
+{
+#if 0
+        /* Example */
+        if (class->name_version == 1 &&
+                        !strcmp(class->name, "lockname"))
+                return 1;
+        if (class->name_version == 1 &&
+                        !strcmp(class->name, "&struct->lockfield"))
+                return 1;
+#endif
+        /* Filter everything else. 1 would be to allow everything else */
+        return 0;
+}
+#endif
+
+static int verbose(struct lock_class *class)
+{
+#if VERBOSE
+        return class_filter(class);
+#endif
+        return 0;
+}
+
+/*
+ * Stack-trace: tightly packed array of stack backtrace
+ * addresses. Protected by the graph_lock.
+ */
+unsigned long nr_stack_trace_entries;
+static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
+
+static void print_lockdep_off(const char *bug_msg)
+{
+        printk(KERN_DEBUG "%s\n", bug_msg);
+        printk(KERN_DEBUG "turning off the locking correctness validator.\n");
+        printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
+}
+
+static int save_trace(struct stack_trace *trace)
+{
+        trace->nr_entries = 0;
+        trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
+        trace->entries = stack_trace + nr_stack_trace_entries;
+
+        trace->skip = 3;
+
+        save_stack_trace(trace);
+
+        /*
+         * Some daft arches put -1 at the end to indicate its a full trace.
+         *
+         * <rant> this is buggy anyway, since it takes a whole extra entry so a
+         * complete trace that maxes out the entries provided will be reported
+         * as incomplete, friggin useless </rant>
+         */
+        if (trace->nr_entries != 0 &&
+            trace->entries[trace->nr_entries-1] == ULONG_MAX)
+                trace->nr_entries--;
+
+        trace->max_entries = trace->nr_entries;
+
+        nr_stack_trace_entries += trace->nr_entries;
+
+        if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
+                if (!debug_locks_off_graph_unlock())
+                        return 0;
+
+                print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
+                dump_stack();
+
+                return 0;
+        }
+
+        return 1;
+}
+
+unsigned int nr_hardirq_chains;
+unsigned int nr_softirq_chains;
+unsigned int nr_process_chains;
+unsigned int max_lockdep_depth;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+/*
+ * We cannot printk in early bootup code. Not even early_printk()
+ * might work. So we mark any initialization errors and printk
+ * about it later on, in lockdep_info().
+ */
+static int lockdep_init_error;
+static const char *lock_init_error;
+static unsigned long lockdep_init_trace_data[20];
+static struct stack_trace lockdep_init_trace = {
+        .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
+        .entries = lockdep_init_trace_data,
+};
+
+/*
+ * Various lockdep statistics:
+ */
+DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
+#endif
+
+/*
+ * Locking printouts:
+ */
+
+#define __USAGE(__STATE)                                                \
+        [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
+        [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
+        [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
+        [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
+
+static const char *usage_str[] =
+{
+#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+        [LOCK_USED] = "INITIAL USE",
+};
+
+const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
+{
+        return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
+}
+
+static inline unsigned long lock_flag(enum lock_usage_bit bit)
+{
+        return 1UL << bit;
+}
+
+static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
+{
+        char c = '.';
+
+        if (class->usage_mask & lock_flag(bit + 2))
+                c = '+';
+        if (class->usage_mask & lock_flag(bit)) {
+                c = '-';
+                if (class->usage_mask & lock_flag(bit + 2))
+                        c = '?';
+        }
+
+        return c;
+}
+
+void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
+{
+        int i = 0;
+
+#define LOCKDEP_STATE(__STATE)                                          \
+        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
+        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+
+        usage[i] = '\0';
+}
+
+static void __print_lock_name(struct lock_class *class)
+{
+        char str[KSYM_NAME_LEN];
+        const char *name;
+
+        name = class->name;
+        if (!name) {
+                name = __get_key_name(class->key, str);
+                printk("%s", name);
+        } else {
+                printk("%s", name);
+                if (class->name_version > 1)
+                        printk("#%d", class->name_version);
+                if (class->subclass)
+                        printk("/%d", class->subclass);
+        }
+}
+
+static void print_lock_name(struct lock_class *class)
+{
+        char usage[LOCK_USAGE_CHARS];
+
+        get_usage_chars(class, usage);
+
+        printk(" (");
+        __print_lock_name(class);
+        printk("){%s}", usage);
+}
+
+static void print_lockdep_cache(struct lockdep_map *lock)
+{
+        const char *name;
+        char str[KSYM_NAME_LEN];
+
+        name = lock->name;
+        if (!name)
+                name = __get_key_name(lock->key->subkeys, str);
+
+        printk("%s", name);
+}
+
+static void print_lock(struct held_lock *hlock)
+{
+        print_lock_name(hlock_class(hlock));
+        printk(", at: ");
+        print_ip_sym(hlock->acquire_ip);
+}
+
+static void lockdep_print_held_locks(struct task_struct *curr)
+{
+        int i, depth = curr->lockdep_depth;
+
+        if (!depth) {
+                printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
+                return;
+        }
+        printk("%d lock%s held by %s/%d:\n",
+                depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
+
+        for (i = 0; i < depth; i++) {
+                printk(" #%d: ", i);
+                print_lock(curr->held_locks + i);
+        }
+}
+
+static void print_kernel_ident(void)
+{
+        printk("%s %.*s %s\n", init_utsname()->release,
+                (int)strcspn(init_utsname()->version, " "),
+                init_utsname()->version,
+                print_tainted());
+}
+
+static int very_verbose(struct lock_class *class)
+{
+#if VERY_VERBOSE
+        return class_filter(class);
+#endif
+        return 0;
+}
+
+/*
+ * Is this the address of a static object:
+ */
+static int static_obj(void *obj)
+{
+        unsigned long start = (unsigned long) &_stext,
+                      end   = (unsigned long) &_end,
+                      addr  = (unsigned long) obj;
+
+        /*
+         * static variable?
+         */
+        if ((addr >= start) && (addr < end))
+                return 1;
+
+        if (arch_is_kernel_data(addr))
+                return 1;
+
+        /*
+         * in-kernel percpu var?
+         */
+        if (is_kernel_percpu_address(addr))
+                return 1;
+
+        /*
+         * module static or percpu var?
+         */
+        return is_module_address(addr) || is_module_percpu_address(addr);
+}
+
+/*
+ * To make lock name printouts unique, we calculate a unique
+ * class->name_version generation counter:
+ */
+static int count_matching_names(struct lock_class *new_class)
+{
+        struct lock_class *class;
+        int count = 0;
+
+        if (!new_class->name)
+                return 0;
+
+        list_for_each_entry(class, &all_lock_classes, lock_entry) {
+                if (new_class->key - new_class->subclass == class->key)
+                        return class->name_version;
+                if (class->name && !strcmp(class->name, new_class->name))
+                        count = max(count, class->name_version);
+        }
+
+        return count + 1;
+}
+
+/*
+ * Register a lock's class in the hash-table, if the class is not present
+ * yet. Otherwise we look it up. We cache the result in the lock object
+ * itself, so actual lookup of the hash should be once per lock object.
+ */
+static inline struct lock_class *
+look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
+{
+        struct lockdep_subclass_key *key;
+        struct list_head *hash_head;
+        struct lock_class *class;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+        /*
+         * If the architecture calls into lockdep before initializing
+         * the hashes then we'll warn about it later. (we cannot printk
+         * right now)
+         */
+        if (unlikely(!lockdep_initialized)) {
+                lockdep_init();
+                lockdep_init_error = 1;
+                lock_init_error = lock->name;
+                save_stack_trace(&lockdep_init_trace);
+        }
+#endif
+
+        if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
+                debug_locks_off();
+                printk(KERN_ERR
+                        "BUG: looking up invalid subclass: %u\n", subclass);
+                printk(KERN_ERR
+                        "turning off the locking correctness validator.\n");
+                dump_stack();
+                return NULL;
+        }
+
+        /*
+         * Static locks do not have their class-keys yet - for them the key
+         * is the lock object itself:
+         */
+        if (unlikely(!lock->key))
+                lock->key = (void *)lock;
+
+        /*
+         * NOTE: the class-key must be unique. For dynamic locks, a static
+         * lock_class_key variable is passed in through the mutex_init()
+         * (or spin_lock_init()) call - which acts as the key. For static
+         * locks we use the lock object itself as the key.
+         */
+        BUILD_BUG_ON(sizeof(struct lock_class_key) >
+                        sizeof(struct lockdep_map));
+
+        key = lock->key->subkeys + subclass;
+
+        hash_head = classhashentry(key);
+
+        /*
+         * We can walk the hash lockfree, because the hash only
+         * grows, and we are careful when adding entries to the end:
+         */
+        list_for_each_entry(class, hash_head, hash_entry) {
+                if (class->key == key) {
+                        /*
+                         * Huh! same key, different name? Did someone trample
+                         * on some memory? We're most confused.
+                         */
+                        WARN_ON_ONCE(class->name != lock->name);
+                        return class;
+                }
+        }
+
+        return NULL;
+}
+
+/*
+ * Register a lock's class in the hash-table, if the class is not present
+ * yet. Otherwise we look it up. We cache the result in the lock object
+ * itself, so actual lookup of the hash should be once per lock object.
+ */
+static inline struct lock_class *
+register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
+{
+        struct lockdep_subclass_key *key;
+        struct list_head *hash_head;
+        struct lock_class *class;
+        unsigned long flags;
+
+        class = look_up_lock_class(lock, subclass);
+        if (likely(class))
+                goto out_set_class_cache;
+
+        /*
+         * Debug-check: all keys must be persistent!
+         */
+        if (!static_obj(lock->key)) {
+                debug_locks_off();
+                printk("INFO: trying to register non-static key.\n");
+                printk("the code is fine but needs lockdep annotation.\n");
+                printk("turning off the locking correctness validator.\n");
+                dump_stack();
+
+                return NULL;
+        }
+
+        key = lock->key->subkeys + subclass;
+        hash_head = classhashentry(key);
+
+        raw_local_irq_save(flags);
+        if (!graph_lock()) {
+                raw_local_irq_restore(flags);
+                return NULL;
+        }
+        /*
+         * We have to do the hash-walk again, to avoid races
+         * with another CPU:
+         */
+        list_for_each_entry(class, hash_head, hash_entry)
+                if (class->key == key)
+                        goto out_unlock_set;
+        /*
+         * Allocate a new key from the static array, and add it to
+         * the hash:
+         */
+        if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
+                if (!debug_locks_off_graph_unlock()) {
+                        raw_local_irq_restore(flags);
+                        return NULL;
+                }
+                raw_local_irq_restore(flags);
+
+                print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
+                dump_stack();
+                return NULL;
+        }
+        class = lock_classes + nr_lock_classes++;
+        debug_atomic_inc(nr_unused_locks);
+        class->key = key;
+        class->name = lock->name;
+        class->subclass = subclass;
+        INIT_LIST_HEAD(&class->lock_entry);
+        INIT_LIST_HEAD(&class->locks_before);
+        INIT_LIST_HEAD(&class->locks_after);
+        class->name_version = count_matching_names(class);
+        /*
+         * We use RCU's safe list-add method to make
+         * parallel walking of the hash-list safe:
+         */
+        list_add_tail_rcu(&class->hash_entry, hash_head);
+        /*
+         * Add it to the global list of classes:
+         */
+        list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
+
+        if (verbose(class)) {
+                graph_unlock();
+                raw_local_irq_restore(flags);
+
+                printk("\nnew class %p: %s", class->key, class->name);
+                if (class->name_version > 1)
+                        printk("#%d", class->name_version);
+                printk("\n");
+                dump_stack();
+
+                raw_local_irq_save(flags);
+                if (!graph_lock()) {
+                        raw_local_irq_restore(flags);
+                        return NULL;
+                }
+        }
+out_unlock_set:
+        graph_unlock();
+        raw_local_irq_restore(flags);
+
+out_set_class_cache:
+        if (!subclass || force)
+                lock->class_cache[0] = class;
+        else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
+                lock->class_cache[subclass] = class;
+
+        /*
+         * Hash collision, did we smoke some? We found a class with a matching
+         * hash but the subclass -- which is hashed in -- didn't match.
+         */
+        if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
+                return NULL;
+
+        return class;
+}
+
+#ifdef CONFIG_PROVE_LOCKING
+/*
+ * Allocate a lockdep entry. (assumes the graph_lock held, returns
+ * with NULL on failure)
+ */
+static struct lock_list *alloc_list_entry(void)
+{
+        if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
+                if (!debug_locks_off_graph_unlock())
+                        return NULL;
+
+                print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
+                dump_stack();
+                return NULL;
+        }
+        return list_entries + nr_list_entries++;
+}
+
+/*
+ * Add a new dependency to the head of the list:
+ */
+static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
+                            struct list_head *head, unsigned long ip,
+                            int distance, struct stack_trace *trace)
+{
+        struct lock_list *entry;
+        /*
+         * Lock not present yet - get a new dependency struct and
+         * add it to the list:
+         */
+        entry = alloc_list_entry();
+        if (!entry)
+                return 0;
+
+        entry->class = this;
+        entry->distance = distance;
+        entry->trace = *trace;
+        /*
+         * Since we never remove from the dependency list, the list can
+         * be walked lockless by other CPUs, it's only allocation
+         * that must be protected by the spinlock. But this also means
+         * we must make new entries visible only once writes to the
+         * entry become visible - hence the RCU op:
+         */
+        list_add_tail_rcu(&entry->entry, head);
+
+        return 1;
+}
+
+/*
+ * For good efficiency of modular, we use power of 2
+ */
+#define MAX_CIRCULAR_QUEUE_SIZE         4096UL
+#define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
+
+/*
+ * The circular_queue and helpers is used to implement the
+ * breadth-first search(BFS)algorithem, by which we can build
+ * the shortest path from the next lock to be acquired to the
+ * previous held lock if there is a circular between them.
+ */
+struct circular_queue {
+        unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
+        unsigned int  front, rear;
+};
+
+static struct circular_queue lock_cq;
+
+unsigned int max_bfs_queue_depth;
+
+static unsigned int lockdep_dependency_gen_id;
+
+static inline void __cq_init(struct circular_queue *cq)
+{
+        cq->front = cq->rear = 0;
+        lockdep_dependency_gen_id++;
+}
+
+static inline int __cq_empty(struct circular_queue *cq)
+{
+        return (cq->front == cq->rear);
+}
+
+static inline int __cq_full(struct circular_queue *cq)
+{
+        return ((cq->rear + 1) & CQ_MASK) == cq->front;
+}
+
+static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
+{
+        if (__cq_full(cq))
+                return -1;
+
+        cq->element[cq->rear] = elem;
+        cq->rear = (cq->rear + 1) & CQ_MASK;
+        return 0;
+}
+
+static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
+{
+        if (__cq_empty(cq))
+                return -1;
+
+        *elem = cq->element[cq->front];
+        cq->front = (cq->front + 1) & CQ_MASK;
+        return 0;
+}
+
+static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
+{
+        return (cq->rear - cq->front) & CQ_MASK;
+}
+
+static inline void mark_lock_accessed(struct lock_list *lock,
+                                        struct lock_list *parent)
+{
+        unsigned long nr;
+
+        nr = lock - list_entries;
+        WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
+        lock->parent = parent;
+        lock->class->dep_gen_id = lockdep_dependency_gen_id;
+}
+
+static inline unsigned long lock_accessed(struct lock_list *lock)
+{
+        unsigned long nr;
+
+        nr = lock - list_entries;
+        WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
+        return lock->class->dep_gen_id == lockdep_dependency_gen_id;
+}
+
+static inline struct lock_list *get_lock_parent(struct lock_list *child)
+{
+        return child->parent;
+}
+
+static inline int get_lock_depth(struct lock_list *child)
+{
+        int depth = 0;
+        struct lock_list *parent;
+
+        while ((parent = get_lock_parent(child))) {
+                child = parent;
+                depth++;
+        }
+        return depth;
+}
+
+static int __bfs(struct lock_list *source_entry,
+                 void *data,
+                 int (*match)(struct lock_list *entry, void *data),
+                 struct lock_list **target_entry,
+                 int forward)
+{
+        struct lock_list *entry;
+        struct list_head *head;
+        struct circular_queue *cq = &lock_cq;
+        int ret = 1;
+
+        if (match(source_entry, data)) {
+                *target_entry = source_entry;
+                ret = 0;
+                goto exit;
+        }
+
+        if (forward)
+                head = &source_entry->class->locks_after;
+        else
+                head = &source_entry->class->locks_before;
+
+        if (list_empty(head))
+                goto exit;
+
+        __cq_init(cq);
+        __cq_enqueue(cq, (unsigned long)source_entry);
+
+        while (!__cq_empty(cq)) {
+                struct lock_list *lock;
+
+                __cq_dequeue(cq, (unsigned long *)&lock);
+
+                if (!lock->class) {
+                        ret = -2;
+                        goto exit;
+                }
+
+                if (forward)
+                        head = &lock->class->locks_after;
+                else
+                        head = &lock->class->locks_before;
+
+                list_for_each_entry(entry, head, entry) {
+                        if (!lock_accessed(entry)) {
+                                unsigned int cq_depth;
+                                mark_lock_accessed(entry, lock);
+                                if (match(entry, data)) {
+                                        *target_entry = entry;
+                                        ret = 0;
+                                        goto exit;
+                                }
+
+                                if (__cq_enqueue(cq, (unsigned long)entry)) {
+                                        ret = -1;
+                                        goto exit;
+                                }
+                                cq_depth = __cq_get_elem_count(cq);
+                                if (max_bfs_queue_depth < cq_depth)
+                                        max_bfs_queue_depth = cq_depth;
+                        }
+                }
+        }
+exit:
+        return ret;
+}
+
+static inline int __bfs_forwards(struct lock_list *src_entry,
+                        void *data,
+                        int (*match)(struct lock_list *entry, void *data),
+                        struct lock_list **target_entry)
+{
+        return __bfs(src_entry, data, match, target_entry, 1);
+
+}
+
+static inline int __bfs_backwards(struct lock_list *src_entry,
+                        void *data,
+                        int (*match)(struct lock_list *entry, void *data),
+                        struct lock_list **target_entry)
+{
+        return __bfs(src_entry, data, match, target_entry, 0);
+
+}
+
+/*
+ * Recursive, forwards-direction lock-dependency checking, used for
+ * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
+ * checking.
+ */
+
+/*
+ * Print a dependency chain entry (this is only done when a deadlock
+ * has been detected):
+ */
+static noinline int
+print_circular_bug_entry(struct lock_list *target, int depth)
+{
+        if (debug_locks_silent)
+                return 0;
+        printk("\n-> #%u", depth);
+        print_lock_name(target->class);
+        printk(":\n");
+        print_stack_trace(&target->trace, 6);
+
+        return 0;
+}
+
+static void
+print_circular_lock_scenario(struct held_lock *src,
+                             struct held_lock *tgt,
+                             struct lock_list *prt)
+{
+        struct lock_class *source = hlock_class(src);
+        struct lock_class *target = hlock_class(tgt);
+        struct lock_class *parent = prt->class;
+
+        /*
+         * A direct locking problem where unsafe_class lock is taken
+         * directly by safe_class lock, then all we need to show
+         * is the deadlock scenario, as it is obvious that the
+         * unsafe lock is taken under the safe lock.
+         *
+         * But if there is a chain instead, where the safe lock takes
+         * an intermediate lock (middle_class) where this lock is
+         * not the same as the safe lock, then the lock chain is
+         * used to describe the problem. Otherwise we would need
+         * to show a different CPU case for each link in the chain
+         * from the safe_class lock to the unsafe_class lock.
+         */
+        if (parent != source) {
+                printk("Chain exists of:\n  ");
+                __print_lock_name(source);
+                printk(" --> ");
+                __print_lock_name(parent);
+                printk(" --> ");
+                __print_lock_name(target);
+                printk("\n\n");
+        }
+
+        printk(" Possible unsafe locking scenario:\n\n");
+        printk("       CPU0                    CPU1\n");
+        printk("       ----                    ----\n");
+        printk("  lock(");
+        __print_lock_name(target);
+        printk(");\n");
+        printk("                               lock(");
+        __print_lock_name(parent);
+        printk(");\n");
+        printk("                               lock(");
+        __print_lock_name(target);
+        printk(");\n");
+        printk("  lock(");
+        __print_lock_name(source);
+        printk(");\n");
+        printk("\n *** DEADLOCK ***\n\n");
+}
+
+/*
+ * When a circular dependency is detected, print the
+ * header first:
+ */
+static noinline int
+print_circular_bug_header(struct lock_list *entry, unsigned int depth,
+                        struct held_lock *check_src,
+                        struct held_lock *check_tgt)
+{
+        struct task_struct *curr = current;
+
+        if (debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("======================================================\n");
+        printk("[ INFO: possible circular locking dependency detected ]\n");
+        print_kernel_ident();
+        printk("-------------------------------------------------------\n");
+        printk("%s/%d is trying to acquire lock:\n",
+                curr->comm, task_pid_nr(curr));
+        print_lock(check_src);
+        printk("\nbut task is already holding lock:\n");
+        print_lock(check_tgt);
+        printk("\nwhich lock already depends on the new lock.\n\n");
+        printk("\nthe existing dependency chain (in reverse order) is:\n");
+
+        print_circular_bug_entry(entry, depth);
+
+        return 0;
+}
+
+static inline int class_equal(struct lock_list *entry, void *data)
+{
+        return entry->class == data;
+}
+
+static noinline int print_circular_bug(struct lock_list *this,
+                                struct lock_list *target,
+                                struct held_lock *check_src,
+                                struct held_lock *check_tgt)
+{
+        struct task_struct *curr = current;
+        struct lock_list *parent;
+        struct lock_list *first_parent;
+        int depth;
+
+        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+                return 0;
+
+        if (!save_trace(&this->trace))
+                return 0;
+
+        depth = get_lock_depth(target);
+
+        print_circular_bug_header(target, depth, check_src, check_tgt);
+
+        parent = get_lock_parent(target);
+        first_parent = parent;
+
+        while (parent) {
+                print_circular_bug_entry(parent, --depth);
+                parent = get_lock_parent(parent);
+        }
+
+        printk("\nother info that might help us debug this:\n\n");
+        print_circular_lock_scenario(check_src, check_tgt,
+                                     first_parent);
+
+        lockdep_print_held_locks(curr);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+static noinline int print_bfs_bug(int ret)
+{
+        if (!debug_locks_off_graph_unlock())
+                return 0;
+
+        /*
+         * Breadth-first-search failed, graph got corrupted?
+         */
+        WARN(1, "lockdep bfs error:%d\n", ret);
+
+        return 0;
+}
+
+static int noop_count(struct lock_list *entry, void *data)
+{
+        (*(unsigned long *)data)++;
+        return 0;
+}
+
+static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
+{
+        unsigned long  count = 0;
+        struct lock_list *uninitialized_var(target_entry);
+
+        __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
+
+        return count;
+}
+unsigned long lockdep_count_forward_deps(struct lock_class *class)
+{
+        unsigned long ret, flags;
+        struct lock_list this;
+
+        this.parent = NULL;
+        this.class = class;
+
+        local_irq_save(flags);
+        arch_spin_lock(&lockdep_lock);
+        ret = __lockdep_count_forward_deps(&this);
+        arch_spin_unlock(&lockdep_lock);
+        local_irq_restore(flags);
+
+        return ret;
+}
+
+static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
+{
+        unsigned long  count = 0;
+        struct lock_list *uninitialized_var(target_entry);
+
+        __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
+
+        return count;
+}
+
+unsigned long lockdep_count_backward_deps(struct lock_class *class)
+{
+        unsigned long ret, flags;
+        struct lock_list this;
+
+        this.parent = NULL;
+        this.class = class;
+
+        local_irq_save(flags);
+        arch_spin_lock(&lockdep_lock);
+        ret = __lockdep_count_backward_deps(&this);
+        arch_spin_unlock(&lockdep_lock);
+        local_irq_restore(flags);
+
+        return ret;
+}
+
+/*
+ * Prove that the dependency graph starting at <entry> can not
+ * lead to <target>. Print an error and return 0 if it does.
+ */
+static noinline int
+check_noncircular(struct lock_list *root, struct lock_class *target,
+                struct lock_list **target_entry)
+{
+        int result;
+
+        debug_atomic_inc(nr_cyclic_checks);
+
+        result = __bfs_forwards(root, target, class_equal, target_entry);
+
+        return result;
+}
+
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+/*
+ * Forwards and backwards subgraph searching, for the purposes of
+ * proving that two subgraphs can be connected by a new dependency
+ * without creating any illegal irq-safe -> irq-unsafe lock dependency.
+ */
+
+static inline int usage_match(struct lock_list *entry, void *bit)
+{
+        return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
+}
+
+
+
+/*
+ * Find a node in the forwards-direction dependency sub-graph starting
+ * at @root->class that matches @bit.
+ *
+ * Return 0 if such a node exists in the subgraph, and put that node
+ * into *@target_entry.
+ *
+ * Return 1 otherwise and keep *@target_entry unchanged.
+ * Return <0 on error.
+ */
+static int
+find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
+                        struct lock_list **target_entry)
+{
+        int result;
+
+        debug_atomic_inc(nr_find_usage_forwards_checks);
+
+        result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
+
+        return result;
+}
+
+/*
+ * Find a node in the backwards-direction dependency sub-graph starting
+ * at @root->class that matches @bit.
+ *
+ * Return 0 if such a node exists in the subgraph, and put that node
+ * into *@target_entry.
+ *
+ * Return 1 otherwise and keep *@target_entry unchanged.
+ * Return <0 on error.
+ */
+static int
+find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
+                        struct lock_list **target_entry)
+{
+        int result;
+
+        debug_atomic_inc(nr_find_usage_backwards_checks);
+
+        result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
+
+        return result;
+}
+
+static void print_lock_class_header(struct lock_class *class, int depth)
+{
+        int bit;
+
+        printk("%*s->", depth, "");
+        print_lock_name(class);
+        printk(" ops: %lu", class->ops);
+        printk(" {\n");
+
+        for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
+                if (class->usage_mask & (1 << bit)) {
+                        int len = depth;
+
+                        len += printk("%*s   %s", depth, "", usage_str[bit]);
+                        len += printk(" at:\n");
+                        print_stack_trace(class->usage_traces + bit, len);
+                }
+        }
+        printk("%*s }\n", depth, "");
+
+        printk("%*s ... key      at: ",depth,"");
+        print_ip_sym((unsigned long)class->key);
+}
+
+/*
+ * printk the shortest lock dependencies from @start to @end in reverse order:
+ */
+static void __used
+print_shortest_lock_dependencies(struct lock_list *leaf,
+                                struct lock_list *root)
+{
+        struct lock_list *entry = leaf;
+        int depth;
+
+        /*compute depth from generated tree by BFS*/
+        depth = get_lock_depth(leaf);
+
+        do {
+                print_lock_class_header(entry->class, depth);
+                printk("%*s ... acquired at:\n", depth, "");
+                print_stack_trace(&entry->trace, 2);
+                printk("\n");
+
+                if (depth == 0 && (entry != root)) {
+                        printk("lockdep:%s bad path found in chain graph\n", __func__);
+                        break;
+                }
+
+                entry = get_lock_parent(entry);
+                depth--;
+        } while (entry && (depth >= 0));
+
+        return;
+}
+
+static void
+print_irq_lock_scenario(struct lock_list *safe_entry,
+                        struct lock_list *unsafe_entry,
+                        struct lock_class *prev_class,
+                        struct lock_class *next_class)
+{
+        struct lock_class *safe_class = safe_entry->class;
+        struct lock_class *unsafe_class = unsafe_entry->class;
+        struct lock_class *middle_class = prev_class;
+
+        if (middle_class == safe_class)
+                middle_class = next_class;
+
+        /*
+         * A direct locking problem where unsafe_class lock is taken
+         * directly by safe_class lock, then all we need to show
+         * is the deadlock scenario, as it is obvious that the
+         * unsafe lock is taken under the safe lock.
+         *
+         * But if there is a chain instead, where the safe lock takes
+         * an intermediate lock (middle_class) where this lock is
+         * not the same as the safe lock, then the lock chain is
+         * used to describe the problem. Otherwise we would need
+         * to show a different CPU case for each link in the chain
+         * from the safe_class lock to the unsafe_class lock.
+         */
+        if (middle_class != unsafe_class) {
+                printk("Chain exists of:\n  ");
+                __print_lock_name(safe_class);
+                printk(" --> ");
+                __print_lock_name(middle_class);
+                printk(" --> ");
+                __print_lock_name(unsafe_class);
+                printk("\n\n");
+        }
+
+        printk(" Possible interrupt unsafe locking scenario:\n\n");
+        printk("       CPU0                    CPU1\n");
+        printk("       ----                    ----\n");
+        printk("  lock(");
+        __print_lock_name(unsafe_class);
+        printk(");\n");
+        printk("                               local_irq_disable();\n");
+        printk("                               lock(");
+        __print_lock_name(safe_class);
+        printk(");\n");
+        printk("                               lock(");
+        __print_lock_name(middle_class);
+        printk(");\n");
+        printk("  <Interrupt>\n");
+        printk("    lock(");
+        __print_lock_name(safe_class);
+        printk(");\n");
+        printk("\n *** DEADLOCK ***\n\n");
+}
+
+static int
+print_bad_irq_dependency(struct task_struct *curr,
+                         struct lock_list *prev_root,
+                         struct lock_list *next_root,
+                         struct lock_list *backwards_entry,
+                         struct lock_list *forwards_entry,
+                         struct held_lock *prev,
+                         struct held_lock *next,
+                         enum lock_usage_bit bit1,
+                         enum lock_usage_bit bit2,
+                         const char *irqclass)
+{
+        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("======================================================\n");
+        printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
+                irqclass, irqclass);
+        print_kernel_ident();
+        printk("------------------------------------------------------\n");
+        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
+                curr->comm, task_pid_nr(curr),
+                curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
+                curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
+                curr->hardirqs_enabled,
+                curr->softirqs_enabled);
+        print_lock(next);
+
+        printk("\nand this task is already holding:\n");
+        print_lock(prev);
+        printk("which would create a new lock dependency:\n");
+        print_lock_name(hlock_class(prev));
+        printk(" ->");
+        print_lock_name(hlock_class(next));
+        printk("\n");
+
+        printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
+                irqclass);
+        print_lock_name(backwards_entry->class);
+        printk("\n... which became %s-irq-safe at:\n", irqclass);
+
+        print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
+
+        printk("\nto a %s-irq-unsafe lock:\n", irqclass);
+        print_lock_name(forwards_entry->class);
+        printk("\n... which became %s-irq-unsafe at:\n", irqclass);
+        printk("...");
+
+        print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
+
+        printk("\nother info that might help us debug this:\n\n");
+        print_irq_lock_scenario(backwards_entry, forwards_entry,
+                                hlock_class(prev), hlock_class(next));
+
+        lockdep_print_held_locks(curr);
+
+        printk("\nthe dependencies between %s-irq-safe lock", irqclass);
+        printk(" and the holding lock:\n");
+        if (!save_trace(&prev_root->trace))
+                return 0;
+        print_shortest_lock_dependencies(backwards_entry, prev_root);
+
+        printk("\nthe dependencies between the lock to be acquired");
+        printk(" and %s-irq-unsafe lock:\n", irqclass);
+        if (!save_trace(&next_root->trace))
+                return 0;
+        print_shortest_lock_dependencies(forwards_entry, next_root);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+static int
+check_usage(struct task_struct *curr, struct held_lock *prev,
+            struct held_lock *next, enum lock_usage_bit bit_backwards,
+            enum lock_usage_bit bit_forwards, const char *irqclass)
+{
+        int ret;
+        struct lock_list this, that;
+        struct lock_list *uninitialized_var(target_entry);
+        struct lock_list *uninitialized_var(target_entry1);
+
+        this.parent = NULL;
+
+        this.class = hlock_class(prev);
+        ret = find_usage_backwards(&this, bit_backwards, &target_entry);
+        if (ret < 0)
+                return print_bfs_bug(ret);
+        if (ret == 1)
+                return ret;
+
+        that.parent = NULL;
+        that.class = hlock_class(next);
+        ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
+        if (ret < 0)
+                return print_bfs_bug(ret);
+        if (ret == 1)
+                return ret;
+
+        return print_bad_irq_dependency(curr, &this, &that,
+                        target_entry, target_entry1,
+                        prev, next,
+                        bit_backwards, bit_forwards, irqclass);
+}
+
+static const char *state_names[] = {
+#define LOCKDEP_STATE(__STATE) \
+        __stringify(__STATE),
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static const char *state_rnames[] = {
+#define LOCKDEP_STATE(__STATE) \
+        __stringify(__STATE)"-READ",
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static inline const char *state_name(enum lock_usage_bit bit)
+{
+        return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
+}
+
+static int exclusive_bit(int new_bit)
+{
+        /*
+         * USED_IN
+         * USED_IN_READ
+         * ENABLED
+         * ENABLED_READ
+         *
+         * bit 0 - write/read
+         * bit 1 - used_in/enabled
+         * bit 2+  state
+         */
+
+        int state = new_bit & ~3;
+        int dir = new_bit & 2;
+
+        /*
+         * keep state, bit flip the direction and strip read.
+         */
+        return state | (dir ^ 2);
+}
+
+static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
+                           struct held_lock *next, enum lock_usage_bit bit)
+{
+        /*
+         * Prove that the new dependency does not connect a hardirq-safe
+         * lock with a hardirq-unsafe lock - to achieve this we search
+         * the backwards-subgraph starting at <prev>, and the
+         * forwards-subgraph starting at <next>:
+         */
+        if (!check_usage(curr, prev, next, bit,
+                           exclusive_bit(bit), state_name(bit)))
+                return 0;
+
+        bit++; /* _READ */
+
+        /*
+         * Prove that the new dependency does not connect a hardirq-safe-read
+         * lock with a hardirq-unsafe lock - to achieve this we search
+         * the backwards-subgraph starting at <prev>, and the
+         * forwards-subgraph starting at <next>:
+         */
+        if (!check_usage(curr, prev, next, bit,
+                           exclusive_bit(bit), state_name(bit)))
+                return 0;
+
+        return 1;
+}
+
+static int
+check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
+                struct held_lock *next)
+{
+#define LOCKDEP_STATE(__STATE)                                          \
+        if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
+                return 0;
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+
+        return 1;
+}
+
+static void inc_chains(void)
+{
+        if (current->hardirq_context)
+                nr_hardirq_chains++;
+        else {
+                if (current->softirq_context)
+                        nr_softirq_chains++;
+                else
+                        nr_process_chains++;
+        }
+}
+
+#else
+
+static inline int
+check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
+                struct held_lock *next)
+{
+        return 1;
+}
+
+static inline void inc_chains(void)
+{
+        nr_process_chains++;
+}
+
+#endif
+
+static void
+print_deadlock_scenario(struct held_lock *nxt,
+                             struct held_lock *prv)
+{
+        struct lock_class *next = hlock_class(nxt);
+        struct lock_class *prev = hlock_class(prv);
+
+        printk(" Possible unsafe locking scenario:\n\n");
+        printk("       CPU0\n");
+        printk("       ----\n");
+        printk("  lock(");
+        __print_lock_name(prev);
+        printk(");\n");
+        printk("  lock(");
+        __print_lock_name(next);
+        printk(");\n");
+        printk("\n *** DEADLOCK ***\n\n");
+        printk(" May be due to missing lock nesting notation\n\n");
+}
+
+static int
+print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
+                   struct held_lock *next)
+{
+        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("=============================================\n");
+        printk("[ INFO: possible recursive locking detected ]\n");
+        print_kernel_ident();
+        printk("---------------------------------------------\n");
+        printk("%s/%d is trying to acquire lock:\n",
+                curr->comm, task_pid_nr(curr));
+        print_lock(next);
+        printk("\nbut task is already holding lock:\n");
+        print_lock(prev);
+
+        printk("\nother info that might help us debug this:\n");
+        print_deadlock_scenario(next, prev);
+        lockdep_print_held_locks(curr);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+/*
+ * Check whether we are holding such a class already.
+ *
+ * (Note that this has to be done separately, because the graph cannot
+ * detect such classes of deadlocks.)
+ *
+ * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
+ */
+static int
+check_deadlock(struct task_struct *curr, struct held_lock *next,
+               struct lockdep_map *next_instance, int read)
+{
+        struct held_lock *prev;
+        struct held_lock *nest = NULL;
+        int i;
+
+        for (i = 0; i < curr->lockdep_depth; i++) {
+                prev = curr->held_locks + i;
+
+                if (prev->instance == next->nest_lock)
+                        nest = prev;
+
+                if (hlock_class(prev) != hlock_class(next))
+                        continue;
+
+                /*
+                 * Allow read-after-read recursion of the same
+                 * lock class (i.e. read_lock(lock)+read_lock(lock)):
+                 */
+                if ((read == 2) && prev->read)
+                        return 2;
+
+                /*
+                 * We're holding the nest_lock, which serializes this lock's
+                 * nesting behaviour.
+                 */
+                if (nest)
+                        return 2;
+
+                return print_deadlock_bug(curr, prev, next);
+        }
+        return 1;
+}
+
+/*
+ * There was a chain-cache miss, and we are about to add a new dependency
+ * to a previous lock. We recursively validate the following rules:
+ *
+ *  - would the adding of the <prev> -> <next> dependency create a
+ *    circular dependency in the graph? [== circular deadlock]
+ *
+ *  - does the new prev->next dependency connect any hardirq-safe lock
+ *    (in the full backwards-subgraph starting at <prev>) with any
+ *    hardirq-unsafe lock (in the full forwards-subgraph starting at
+ *    <next>)? [== illegal lock inversion with hardirq contexts]
+ *
+ *  - does the new prev->next dependency connect any softirq-safe lock
+ *    (in the full backwards-subgraph starting at <prev>) with any
+ *    softirq-unsafe lock (in the full forwards-subgraph starting at
+ *    <next>)? [== illegal lock inversion with softirq contexts]
+ *
+ * any of these scenarios could lead to a deadlock.
+ *
+ * Then if all the validations pass, we add the forwards and backwards
+ * dependency.
+ */
+static int
+check_prev_add(struct task_struct *curr, struct held_lock *prev,
+               struct held_lock *next, int distance, int trylock_loop)
+{
+        struct lock_list *entry;
+        int ret;
+        struct lock_list this;
+        struct lock_list *uninitialized_var(target_entry);
+        /*
+         * Static variable, serialized by the graph_lock().
+         *
+         * We use this static variable to save the stack trace in case
+         * we call into this function multiple times due to encountering
+         * trylocks in the held lock stack.
+         */
+        static struct stack_trace trace;
+
+        /*
+         * Prove that the new <prev> -> <next> dependency would not
+         * create a circular dependency in the graph. (We do this by
+         * forward-recursing into the graph starting at <next>, and
+         * checking whether we can reach <prev>.)
+         *
+         * We are using global variables to control the recursion, to
+         * keep the stackframe size of the recursive functions low:
+         */
+        this.class = hlock_class(next);
+        this.parent = NULL;
+        ret = check_noncircular(&this, hlock_class(prev), &target_entry);
+        if (unlikely(!ret))
+                return print_circular_bug(&this, target_entry, next, prev);
+        else if (unlikely(ret < 0))
+                return print_bfs_bug(ret);
+
+        if (!check_prev_add_irq(curr, prev, next))
+                return 0;
+
+        /*
+         * For recursive read-locks we do all the dependency checks,
+         * but we dont store read-triggered dependencies (only
+         * write-triggered dependencies). This ensures that only the
+         * write-side dependencies matter, and that if for example a
+         * write-lock never takes any other locks, then the reads are
+         * equivalent to a NOP.
+         */
+        if (next->read == 2 || prev->read == 2)
+                return 1;
+        /*
+         * Is the <prev> -> <next> dependency already present?
+         *
+         * (this may occur even though this is a new chain: consider
+         *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
+         *  chains - the second one will be new, but L1 already has
+         *  L2 added to its dependency list, due to the first chain.)
+         */
+        list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
+                if (entry->class == hlock_class(next)) {
+                        if (distance == 1)
+                                entry->distance = 1;
+                        return 2;
+                }
+        }
+
+        if (!trylock_loop && !save_trace(&trace))
+                return 0;
+
+        /*
+         * Ok, all validations passed, add the new lock
+         * to the previous lock's dependency list:
+         */
+        ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
+                               &hlock_class(prev)->locks_after,
+                               next->acquire_ip, distance, &trace);
+
+        if (!ret)
+                return 0;
+
+        ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
+                               &hlock_class(next)->locks_before,
+                               next->acquire_ip, distance, &trace);
+        if (!ret)
+                return 0;
+
+        /*
+         * Debugging printouts:
+         */
+        if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
+                graph_unlock();
+                printk("\n new dependency: ");
+                print_lock_name(hlock_class(prev));
+                printk(" => ");
+                print_lock_name(hlock_class(next));
+                printk("\n");
+                dump_stack();
+                return graph_lock();
+        }
+        return 1;
+}
+
+/*
+ * Add the dependency to all directly-previous locks that are 'relevant'.
+ * The ones that are relevant are (in increasing distance from curr):
+ * all consecutive trylock entries and the final non-trylock entry - or
+ * the end of this context's lock-chain - whichever comes first.
+ */
+static int
+check_prevs_add(struct task_struct *curr, struct held_lock *next)
+{
+        int depth = curr->lockdep_depth;
+        int trylock_loop = 0;
+        struct held_lock *hlock;
+
+        /*
+         * Debugging checks.
+         *
+         * Depth must not be zero for a non-head lock:
+         */
+        if (!depth)
+                goto out_bug;
+        /*
+         * At least two relevant locks must exist for this
+         * to be a head:
+         */
+        if (curr->held_locks[depth].irq_context !=
+                        curr->held_locks[depth-1].irq_context)
+                goto out_bug;
+
+        for (;;) {
+                int distance = curr->lockdep_depth - depth + 1;
+                hlock = curr->held_locks + depth-1;
+                /*
+                 * Only non-recursive-read entries get new dependencies
+                 * added:
+                 */
+                if (hlock->read != 2) {
+                        if (!check_prev_add(curr, hlock, next,
+                                                distance, trylock_loop))
+                                return 0;
+                        /*
+                         * Stop after the first non-trylock entry,
+                         * as non-trylock entries have added their
+                         * own direct dependencies already, so this
+                         * lock is connected to them indirectly:
+                         */
+                        if (!hlock->trylock)
+                                break;
+                }
+                depth--;
+                /*
+                 * End of lock-stack?
+                 */
+                if (!depth)
+                        break;
+                /*
+                 * Stop the search if we cross into another context:
+                 */
+                if (curr->held_locks[depth].irq_context !=
+                                curr->held_locks[depth-1].irq_context)
+                        break;
+                trylock_loop = 1;
+        }
+        return 1;
+out_bug:
+        if (!debug_locks_off_graph_unlock())
+                return 0;
+
+        /*
+         * Clearly we all shouldn't be here, but since we made it we
+         * can reliable say we messed up our state. See the above two
+         * gotos for reasons why we could possibly end up here.
+         */
+        WARN_ON(1);
+
+        return 0;
+}
+
+unsigned long nr_lock_chains;
+struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+int nr_chain_hlocks;
+static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
+
+struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
+{
+        return lock_classes + chain_hlocks[chain->base + i];
+}
+
+/*
+ * Look up a dependency chain. If the key is not present yet then
+ * add it and return 1 - in this case the new dependency chain is
+ * validated. If the key is already hashed, return 0.
+ * (On return with 1 graph_lock is held.)
+ */
+static inline int lookup_chain_cache(struct task_struct *curr,
+                                     struct held_lock *hlock,
+                                     u64 chain_key)
+{
+        struct lock_class *class = hlock_class(hlock);
+        struct list_head *hash_head = chainhashentry(chain_key);
+        struct lock_chain *chain;
+        struct held_lock *hlock_curr;
+        int i, j;
+
+        /*
+         * We might need to take the graph lock, ensure we've got IRQs
+         * disabled to make this an IRQ-safe lock.. for recursion reasons
+         * lockdep won't complain about its own locking errors.
+         */
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return 0;
+        /*
+         * We can walk it lock-free, because entries only get added
+         * to the hash:
+         */
+        list_for_each_entry(chain, hash_head, entry) {
+                if (chain->chain_key == chain_key) {
+cache_hit:
+                        debug_atomic_inc(chain_lookup_hits);
+                        if (very_verbose(class))
+                                printk("\nhash chain already cached, key: "
+                                        "%016Lx tail class: [%p] %s\n",
+                                        (unsigned long long)chain_key,
+                                        class->key, class->name);
+                        return 0;
+                }
+        }
+        if (very_verbose(class))
+                printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
+                        (unsigned long long)chain_key, class->key, class->name);
+        /*
+         * Allocate a new chain entry from the static array, and add
+         * it to the hash:
+         */
+        if (!graph_lock())
+                return 0;
+        /*
+         * We have to walk the chain again locked - to avoid duplicates:
+         */
+        list_for_each_entry(chain, hash_head, entry) {
+                if (chain->chain_key == chain_key) {
+                        graph_unlock();
+                        goto cache_hit;
+                }
+        }
+        if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
+                if (!debug_locks_off_graph_unlock())
+                        return 0;
+
+                print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
+                dump_stack();
+                return 0;
+        }
+        chain = lock_chains + nr_lock_chains++;
+        chain->chain_key = chain_key;
+        chain->irq_context = hlock->irq_context;
+        /* Find the first held_lock of current chain */
+        for (i = curr->lockdep_depth - 1; i >= 0; i--) {
+                hlock_curr = curr->held_locks + i;
+                if (hlock_curr->irq_context != hlock->irq_context)
+                        break;
+        }
+        i++;
+        chain->depth = curr->lockdep_depth + 1 - i;
+        if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
+                chain->base = nr_chain_hlocks;
+                nr_chain_hlocks += chain->depth;
+                for (j = 0; j < chain->depth - 1; j++, i++) {
+                        int lock_id = curr->held_locks[i].class_idx - 1;
+                        chain_hlocks[chain->base + j] = lock_id;
+                }
+                chain_hlocks[chain->base + j] = class - lock_classes;
+        }
+        list_add_tail_rcu(&chain->entry, hash_head);
+        debug_atomic_inc(chain_lookup_misses);
+        inc_chains();
+
+        return 1;
+}
+
+static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
+                struct held_lock *hlock, int chain_head, u64 chain_key)
+{
+        /*
+         * Trylock needs to maintain the stack of held locks, but it
+         * does not add new dependencies, because trylock can be done
+         * in any order.
+         *
+         * We look up the chain_key and do the O(N^2) check and update of
+         * the dependencies only if this is a new dependency chain.
+         * (If lookup_chain_cache() returns with 1 it acquires
+         * graph_lock for us)
+         */
+        if (!hlock->trylock && (hlock->check == 2) &&
+            lookup_chain_cache(curr, hlock, chain_key)) {
+                /*
+                 * Check whether last held lock:
+                 *
+                 * - is irq-safe, if this lock is irq-unsafe
+                 * - is softirq-safe, if this lock is hardirq-unsafe
+                 *
+                 * And check whether the new lock's dependency graph
+                 * could lead back to the previous lock.
+                 *
+                 * any of these scenarios could lead to a deadlock. If
+                 * All validations
+                 */
+                int ret = check_deadlock(curr, hlock, lock, hlock->read);
+
+                if (!ret)
+                        return 0;
+                /*
+                 * Mark recursive read, as we jump over it when
+                 * building dependencies (just like we jump over
+                 * trylock entries):
+                 */
+                if (ret == 2)
+                        hlock->read = 2;
+                /*
+                 * Add dependency only if this lock is not the head
+                 * of the chain, and if it's not a secondary read-lock:
+                 */
+                if (!chain_head && ret != 2)
+                        if (!check_prevs_add(curr, hlock))
+                                return 0;
+                graph_unlock();
+        } else
+                /* after lookup_chain_cache(): */
+                if (unlikely(!debug_locks))
+                        return 0;
+
+        return 1;
+}
+#else
+static inline int validate_chain(struct task_struct *curr,
+                struct lockdep_map *lock, struct held_lock *hlock,
+                int chain_head, u64 chain_key)
+{
+        return 1;
+}
+#endif
+
+/*
+ * We are building curr_chain_key incrementally, so double-check
+ * it from scratch, to make sure that it's done correctly:
+ */
+static void check_chain_key(struct task_struct *curr)
+{
+#ifdef CONFIG_DEBUG_LOCKDEP
+        struct held_lock *hlock, *prev_hlock = NULL;
+        unsigned int i, id;
+        u64 chain_key = 0;
+
+        for (i = 0; i < curr->lockdep_depth; i++) {
+                hlock = curr->held_locks + i;
+                if (chain_key != hlock->prev_chain_key) {
+                        debug_locks_off();
+                        /*
+                         * We got mighty confused, our chain keys don't match
+                         * with what we expect, someone trample on our task state?
+                         */
+                        WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
+                                curr->lockdep_depth, i,
+                                (unsigned long long)chain_key,
+                                (unsigned long long)hlock->prev_chain_key);
+                        return;
+                }
+                id = hlock->class_idx - 1;
+                /*
+                 * Whoops ran out of static storage again?
+                 */
+                if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+                        return;
+
+                if (prev_hlock && (prev_hlock->irq_context !=
+                                                        hlock->irq_context))
+                        chain_key = 0;
+                chain_key = iterate_chain_key(chain_key, id);
+                prev_hlock = hlock;
+        }
+        if (chain_key != curr->curr_chain_key) {
+                debug_locks_off();
+                /*
+                 * More smoking hash instead of calculating it, damn see these
+                 * numbers float.. I bet that a pink elephant stepped on my memory.
+                 */
+                WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
+                        curr->lockdep_depth, i,
+                        (unsigned long long)chain_key,
+                        (unsigned long long)curr->curr_chain_key);
+        }
+#endif
+}
+
+static void
+print_usage_bug_scenario(struct held_lock *lock)
+{
+        struct lock_class *class = hlock_class(lock);
+
+        printk(" Possible unsafe locking scenario:\n\n");
+        printk("       CPU0\n");
+        printk("       ----\n");
+        printk("  lock(");
+        __print_lock_name(class);
+        printk(");\n");
+        printk("  <Interrupt>\n");
+        printk("    lock(");
+        __print_lock_name(class);
+        printk(");\n");
+        printk("\n *** DEADLOCK ***\n\n");
+}
+
+static int
+print_usage_bug(struct task_struct *curr, struct held_lock *this,
+                enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
+{
+        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("=================================\n");
+        printk("[ INFO: inconsistent lock state ]\n");
+        print_kernel_ident();
+        printk("---------------------------------\n");
+
+        printk("inconsistent {%s} -> {%s} usage.\n",
+                usage_str[prev_bit], usage_str[new_bit]);
+
+        printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
+                curr->comm, task_pid_nr(curr),
+                trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
+                trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
+                trace_hardirqs_enabled(curr),
+                trace_softirqs_enabled(curr));
+        print_lock(this);
+
+        printk("{%s} state was registered at:\n", usage_str[prev_bit]);
+        print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
+
+        print_irqtrace_events(curr);
+        printk("\nother info that might help us debug this:\n");
+        print_usage_bug_scenario(this);
+
+        lockdep_print_held_locks(curr);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+/*
+ * Print out an error if an invalid bit is set:
+ */
+static inline int
+valid_state(struct task_struct *curr, struct held_lock *this,
+            enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
+{
+        if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
+                return print_usage_bug(curr, this, bad_bit, new_bit);
+        return 1;
+}
+
+static int mark_lock(struct task_struct *curr, struct held_lock *this,
+                     enum lock_usage_bit new_bit);
+
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+
+/*
+ * print irq inversion bug:
+ */
+static int
+print_irq_inversion_bug(struct task_struct *curr,
+                        struct lock_list *root, struct lock_list *other,
+                        struct held_lock *this, int forwards,
+                        const char *irqclass)
+{
+        struct lock_list *entry = other;
+        struct lock_list *middle = NULL;
+        int depth;
+
+        if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("=========================================================\n");
+        printk("[ INFO: possible irq lock inversion dependency detected ]\n");
+        print_kernel_ident();
+        printk("---------------------------------------------------------\n");
+        printk("%s/%d just changed the state of lock:\n",
+                curr->comm, task_pid_nr(curr));
+        print_lock(this);
+        if (forwards)
+                printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
+        else
+                printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
+        print_lock_name(other->class);
+        printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
+
+        printk("\nother info that might help us debug this:\n");
+
+        /* Find a middle lock (if one exists) */
+        depth = get_lock_depth(other);
+        do {
+                if (depth == 0 && (entry != root)) {
+                        printk("lockdep:%s bad path found in chain graph\n", __func__);
+                        break;
+                }
+                middle = entry;
+                entry = get_lock_parent(entry);
+                depth--;
+        } while (entry && entry != root && (depth >= 0));
+        if (forwards)
+                print_irq_lock_scenario(root, other,
+                        middle ? middle->class : root->class, other->class);
+        else
+                print_irq_lock_scenario(other, root,
+                        middle ? middle->class : other->class, root->class);
+
+        lockdep_print_held_locks(curr);
+
+        printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
+        if (!save_trace(&root->trace))
+                return 0;
+        print_shortest_lock_dependencies(other, root);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+/*
+ * Prove that in the forwards-direction subgraph starting at <this>
+ * there is no lock matching <mask>:
+ */
+static int
+check_usage_forwards(struct task_struct *curr, struct held_lock *this,
+                     enum lock_usage_bit bit, const char *irqclass)
+{
+        int ret;
+        struct lock_list root;
+        struct lock_list *uninitialized_var(target_entry);
+
+        root.parent = NULL;
+        root.class = hlock_class(this);
+        ret = find_usage_forwards(&root, bit, &target_entry);
+        if (ret < 0)
+                return print_bfs_bug(ret);
+        if (ret == 1)
+                return ret;
+
+        return print_irq_inversion_bug(curr, &root, target_entry,
+                                        this, 1, irqclass);
+}
+
+/*
+ * Prove that in the backwards-direction subgraph starting at <this>
+ * there is no lock matching <mask>:
+ */
+static int
+check_usage_backwards(struct task_struct *curr, struct held_lock *this,
+                      enum lock_usage_bit bit, const char *irqclass)
+{
+        int ret;
+        struct lock_list root;
+        struct lock_list *uninitialized_var(target_entry);
+
+        root.parent = NULL;
+        root.class = hlock_class(this);
+        ret = find_usage_backwards(&root, bit, &target_entry);
+        if (ret < 0)
+                return print_bfs_bug(ret);
+        if (ret == 1)
+                return ret;
+
+        return print_irq_inversion_bug(curr, &root, target_entry,
+                                        this, 0, irqclass);
+}
+
+void print_irqtrace_events(struct task_struct *curr)
+{
+        printk("irq event stamp: %u\n", curr->irq_events);
+        printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
+        print_ip_sym(curr->hardirq_enable_ip);
+        printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
+        print_ip_sym(curr->hardirq_disable_ip);
+        printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
+        print_ip_sym(curr->softirq_enable_ip);
+        printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
+        print_ip_sym(curr->softirq_disable_ip);
+}
+
+static int HARDIRQ_verbose(struct lock_class *class)
+{
+#if HARDIRQ_VERBOSE
+        return class_filter(class);
+#endif
+        return 0;
+}
+
+static int SOFTIRQ_verbose(struct lock_class *class)
+{
+#if SOFTIRQ_VERBOSE
+        return class_filter(class);
+#endif
+        return 0;
+}
+
+static int RECLAIM_FS_verbose(struct lock_class *class)
+{
+#if RECLAIM_VERBOSE
+        return class_filter(class);
+#endif
+        return 0;
+}
+
+#define STRICT_READ_CHECKS      1
+
+static int (*state_verbose_f[])(struct lock_class *class) = {
+#define LOCKDEP_STATE(__STATE) \
+        __STATE##_verbose,
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static inline int state_verbose(enum lock_usage_bit bit,
+                                struct lock_class *class)
+{
+        return state_verbose_f[bit >> 2](class);
+}
+
+typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
+                             enum lock_usage_bit bit, const char *name);
+
+static int
+mark_lock_irq(struct task_struct *curr, struct held_lock *this,
+                enum lock_usage_bit new_bit)
+{
+        int excl_bit = exclusive_bit(new_bit);
+        int read = new_bit & 1;
+        int dir = new_bit & 2;
+
+        /*
+         * mark USED_IN has to look forwards -- to ensure no dependency
+         * has ENABLED state, which would allow recursion deadlocks.
+         *
+         * mark ENABLED has to look backwards -- to ensure no dependee
+         * has USED_IN state, which, again, would allow  recursion deadlocks.
+         */
+        check_usage_f usage = dir ?
+                check_usage_backwards : check_usage_forwards;
+
+        /*
+         * Validate that this particular lock does not have conflicting
+         * usage states.
+         */
+        if (!valid_state(curr, this, new_bit, excl_bit))
+                return 0;
+
+        /*
+         * Validate that the lock dependencies don't have conflicting usage
+         * states.
+         */
+        if ((!read || !dir || STRICT_READ_CHECKS) &&
+                        !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
+                return 0;
+
+        /*
+         * Check for read in write conflicts
+         */
+        if (!read) {
+                if (!valid_state(curr, this, new_bit, excl_bit + 1))
+                        return 0;
+
+                if (STRICT_READ_CHECKS &&
+                        !usage(curr, this, excl_bit + 1,
+                                state_name(new_bit + 1)))
+                        return 0;
+        }
+
+        if (state_verbose(new_bit, hlock_class(this)))
+                return 2;
+
+        return 1;
+}
+
+enum mark_type {
+#define LOCKDEP_STATE(__STATE)  __STATE,
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+/*
+ * Mark all held locks with a usage bit:
+ */
+static int
+mark_held_locks(struct task_struct *curr, enum mark_type mark)
+{
+        enum lock_usage_bit usage_bit;
+        struct held_lock *hlock;
+        int i;
+
+        for (i = 0; i < curr->lockdep_depth; i++) {
+                hlock = curr->held_locks + i;
+
+                usage_bit = 2 + (mark << 2); /* ENABLED */
+                if (hlock->read)
+                        usage_bit += 1; /* READ */
+
+                BUG_ON(usage_bit >= LOCK_USAGE_STATES);
+
+                if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
+                        continue;
+
+                if (!mark_lock(curr, hlock, usage_bit))
+                        return 0;
+        }
+
+        return 1;
+}
+
+/*
+ * Hardirqs will be enabled:
+ */
+static void __trace_hardirqs_on_caller(unsigned long ip)
+{
+        struct task_struct *curr = current;
+
+        /* we'll do an OFF -> ON transition: */
+        curr->hardirqs_enabled = 1;
+
+        /*
+         * We are going to turn hardirqs on, so set the
+         * usage bit for all held locks:
+         */
+        if (!mark_held_locks(curr, HARDIRQ))
+                return;
+        /*
+         * If we have softirqs enabled, then set the usage
+         * bit for all held locks. (disabled hardirqs prevented
+         * this bit from being set before)
+         */
+        if (curr->softirqs_enabled)
+                if (!mark_held_locks(curr, SOFTIRQ))
+                        return;
+
+        curr->hardirq_enable_ip = ip;
+        curr->hardirq_enable_event = ++curr->irq_events;
+        debug_atomic_inc(hardirqs_on_events);
+}
+
+void trace_hardirqs_on_caller(unsigned long ip)
+{
+        time_hardirqs_on(CALLER_ADDR0, ip);
+
+        if (unlikely(!debug_locks || current->lockdep_recursion))
+                return;
+
+        if (unlikely(current->hardirqs_enabled)) {
+                /*
+                 * Neither irq nor preemption are disabled here
+                 * so this is racy by nature but losing one hit
+                 * in a stat is not a big deal.
+                 */
+                __debug_atomic_inc(redundant_hardirqs_on);
+                return;
+        }
+
+        /*
+         * We're enabling irqs and according to our state above irqs weren't
+         * already enabled, yet we find the hardware thinks they are in fact
+         * enabled.. someone messed up their IRQ state tracing.
+         */
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return;
+
+        /*
+         * See the fine text that goes along with this variable definition.
+         */
+        if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
+                return;
+
+        /*
+         * Can't allow enabling interrupts while in an interrupt handler,
+         * that's general bad form and such. Recursion, limited stack etc..
+         */
+        if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
+                return;
+
+        current->lockdep_recursion = 1;
+        __trace_hardirqs_on_caller(ip);
+        current->lockdep_recursion = 0;
+}
+EXPORT_SYMBOL(trace_hardirqs_on_caller);
+
+void trace_hardirqs_on(void)
+{
+        trace_hardirqs_on_caller(CALLER_ADDR0);
+}
+EXPORT_SYMBOL(trace_hardirqs_on);
+
+/*
+ * Hardirqs were disabled:
+ */
+void trace_hardirqs_off_caller(unsigned long ip)
+{
+        struct task_struct *curr = current;
+
+        time_hardirqs_off(CALLER_ADDR0, ip);
+
+        if (unlikely(!debug_locks || current->lockdep_recursion))
+                return;
+
+        /*
+         * So we're supposed to get called after you mask local IRQs, but for
+         * some reason the hardware doesn't quite think you did a proper job.
+         */
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return;
+
+        if (curr->hardirqs_enabled) {
+                /*
+                 * We have done an ON -> OFF transition:
+                 */
+                curr->hardirqs_enabled = 0;
+                curr->hardirq_disable_ip = ip;
+                curr->hardirq_disable_event = ++curr->irq_events;
+                debug_atomic_inc(hardirqs_off_events);
+        } else
+                debug_atomic_inc(redundant_hardirqs_off);
+}
+EXPORT_SYMBOL(trace_hardirqs_off_caller);
+
+void trace_hardirqs_off(void)
+{
+        trace_hardirqs_off_caller(CALLER_ADDR0);
+}
+EXPORT_SYMBOL(trace_hardirqs_off);
+
+/*
+ * Softirqs will be enabled:
+ */
+void trace_softirqs_on(unsigned long ip)
+{
+        struct task_struct *curr = current;
+
+        if (unlikely(!debug_locks || current->lockdep_recursion))
+                return;
+
+        /*
+         * We fancy IRQs being disabled here, see softirq.c, avoids
+         * funny state and nesting things.
+         */
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return;
+
+        if (curr->softirqs_enabled) {
+                debug_atomic_inc(redundant_softirqs_on);
+                return;
+        }
+
+        current->lockdep_recursion = 1;
+        /*
+         * We'll do an OFF -> ON transition:
+         */
+        curr->softirqs_enabled = 1;
+        curr->softirq_enable_ip = ip;
+        curr->softirq_enable_event = ++curr->irq_events;
+        debug_atomic_inc(softirqs_on_events);
+        /*
+         * We are going to turn softirqs on, so set the
+         * usage bit for all held locks, if hardirqs are
+         * enabled too:
+         */
+        if (curr->hardirqs_enabled)
+                mark_held_locks(curr, SOFTIRQ);
+        current->lockdep_recursion = 0;
+}
+
+/*
+ * Softirqs were disabled:
+ */
+void trace_softirqs_off(unsigned long ip)
+{
+        struct task_struct *curr = current;
+
+        if (unlikely(!debug_locks || current->lockdep_recursion))
+                return;
+
+        /*
+         * We fancy IRQs being disabled here, see softirq.c
+         */
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return;
+
+        if (curr->softirqs_enabled) {
+                /*
+                 * We have done an ON -> OFF transition:
+                 */
+                curr->softirqs_enabled = 0;
+                curr->softirq_disable_ip = ip;
+                curr->softirq_disable_event = ++curr->irq_events;
+                debug_atomic_inc(softirqs_off_events);
+                /*
+                 * Whoops, we wanted softirqs off, so why aren't they?
+                 */
+                DEBUG_LOCKS_WARN_ON(!softirq_count());
+        } else
+                debug_atomic_inc(redundant_softirqs_off);
+}
+
+static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
+{
+        struct task_struct *curr = current;
+
+        if (unlikely(!debug_locks))
+                return;
+
+        /* no reclaim without waiting on it */
+        if (!(gfp_mask & __GFP_WAIT))
+                return;
+
+        /* this guy won't enter reclaim */
+        if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
+                return;
+
+        /* We're only interested __GFP_FS allocations for now */
+        if (!(gfp_mask & __GFP_FS))
+                return;
+
+        /*
+         * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
+         */
+        if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
+                return;
+
+        mark_held_locks(curr, RECLAIM_FS);
+}
+
+static void check_flags(unsigned long flags);
+
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+        unsigned long flags;
+
+        if (unlikely(current->lockdep_recursion))
+                return;
+
+        raw_local_irq_save(flags);
+        check_flags(flags);
+        current->lockdep_recursion = 1;
+        __lockdep_trace_alloc(gfp_mask, flags);
+        current->lockdep_recursion = 0;
+        raw_local_irq_restore(flags);
+}
+
+static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
+{
+        /*
+         * If non-trylock use in a hardirq or softirq context, then
+         * mark the lock as used in these contexts:
+         */
+        if (!hlock->trylock) {
+                if (hlock->read) {
+                        if (curr->hardirq_context)
+                                if (!mark_lock(curr, hlock,
+                                                LOCK_USED_IN_HARDIRQ_READ))
+                                        return 0;
+                        if (curr->softirq_context)
+                                if (!mark_lock(curr, hlock,
+                                                LOCK_USED_IN_SOFTIRQ_READ))
+                                        return 0;
+                } else {
+                        if (curr->hardirq_context)
+                                if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
+                                        return 0;
+                        if (curr->softirq_context)
+                                if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
+                                        return 0;
+                }
+        }
+        if (!hlock->hardirqs_off) {
+                if (hlock->read) {
+                        if (!mark_lock(curr, hlock,
+                                        LOCK_ENABLED_HARDIRQ_READ))
+                                return 0;
+                        if (curr->softirqs_enabled)
+                                if (!mark_lock(curr, hlock,
+                                                LOCK_ENABLED_SOFTIRQ_READ))
+                                        return 0;
+                } else {
+                        if (!mark_lock(curr, hlock,
+                                        LOCK_ENABLED_HARDIRQ))
+                                return 0;
+                        if (curr->softirqs_enabled)
+                                if (!mark_lock(curr, hlock,
+                                                LOCK_ENABLED_SOFTIRQ))
+                                        return 0;
+                }
+        }
+
+        /*
+         * We reuse the irq context infrastructure more broadly as a general
+         * context checking code. This tests GFP_FS recursion (a lock taken
+         * during reclaim for a GFP_FS allocation is held over a GFP_FS
+         * allocation).
+         */
+        if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
+                if (hlock->read) {
+                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
+                                        return 0;
+                } else {
+                        if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
+                                        return 0;
+                }
+        }
+
+        return 1;
+}
+
+static int separate_irq_context(struct task_struct *curr,
+                struct held_lock *hlock)
+{
+        unsigned int depth = curr->lockdep_depth;
+
+        /*
+         * Keep track of points where we cross into an interrupt context:
+         */
+        hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
+                                curr->softirq_context;
+        if (depth) {
+                struct held_lock *prev_hlock;
+
+                prev_hlock = curr->held_locks + depth-1;
+                /*
+                 * If we cross into another context, reset the
+                 * hash key (this also prevents the checking and the
+                 * adding of the dependency to 'prev'):
+                 */
+                if (prev_hlock->irq_context != hlock->irq_context)
+                        return 1;
+        }
+        return 0;
+}
+
+#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
+
+static inline
+int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
+                enum lock_usage_bit new_bit)
+{
+        WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
+        return 1;
+}
+
+static inline int mark_irqflags(struct task_struct *curr,
+                struct held_lock *hlock)
+{
+        return 1;
+}
+
+static inline int separate_irq_context(struct task_struct *curr,
+                struct held_lock *hlock)
+{
+        return 0;
+}
+
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+}
+
+#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
+
+/*
+ * Mark a lock with a usage bit, and validate the state transition:
+ */
+static int mark_lock(struct task_struct *curr, struct held_lock *this,
+                             enum lock_usage_bit new_bit)
+{
+        unsigned int new_mask = 1 << new_bit, ret = 1;
+
+        /*
+         * If already set then do not dirty the cacheline,
+         * nor do any checks:
+         */
+        if (likely(hlock_class(this)->usage_mask & new_mask))
+                return 1;
+
+        if (!graph_lock())
+                return 0;
+        /*
+         * Make sure we didn't race:
+         */
+        if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
+                graph_unlock();
+                return 1;
+        }
+
+        hlock_class(this)->usage_mask |= new_mask;
+
+        if (!save_trace(hlock_class(this)->usage_traces + new_bit))
+                return 0;
+
+        switch (new_bit) {
+#define LOCKDEP_STATE(__STATE)                  \
+        case LOCK_USED_IN_##__STATE:            \
+        case LOCK_USED_IN_##__STATE##_READ:     \
+        case LOCK_ENABLED_##__STATE:            \
+        case LOCK_ENABLED_##__STATE##_READ:
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+                ret = mark_lock_irq(curr, this, new_bit);
+                if (!ret)
+                        return 0;
+                break;
+        case LOCK_USED:
+                debug_atomic_dec(nr_unused_locks);
+                break;
+        default:
+                if (!debug_locks_off_graph_unlock())
+                        return 0;
+                WARN_ON(1);
+                return 0;
+        }
+
+        graph_unlock();
+
+        /*
+         * We must printk outside of the graph_lock:
+         */
+        if (ret == 2) {
+                printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
+                print_lock(this);
+                print_irqtrace_events(curr);
+                dump_stack();
+        }
+
+        return ret;
+}
+
+/*
+ * Initialize a lock instance's lock-class mapping info:
+ */
+void lockdep_init_map(struct lockdep_map *lock, const char *name,
+                      struct lock_class_key *key, int subclass)
+{
+        int i;
+
+        kmemcheck_mark_initialized(lock, sizeof(*lock));
+
+        for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
+                lock->class_cache[i] = NULL;
+
+#ifdef CONFIG_LOCK_STAT
+        lock->cpu = raw_smp_processor_id();
+#endif
+
+        /*
+         * Can't be having no nameless bastards around this place!
+         */
+        if (DEBUG_LOCKS_WARN_ON(!name)) {
+                lock->name = "NULL";
+                return;
+        }
+
+        lock->name = name;
+
+        /*
+         * No key, no joy, we need to hash something.
+         */
+        if (DEBUG_LOCKS_WARN_ON(!key))
+                return;
+        /*
+         * Sanity check, the lock-class key must be persistent:
+         */
+        if (!static_obj(key)) {
+                printk("BUG: key %p not in .data!\n", key);
+                /*
+                 * What it says above ^^^^^, I suggest you read it.
+                 */
+                DEBUG_LOCKS_WARN_ON(1);
+                return;
+        }
+        lock->key = key;
+
+        if (unlikely(!debug_locks))
+                return;
+
+        if (subclass)
+                register_lock_class(lock, subclass, 1);
+}
+EXPORT_SYMBOL_GPL(lockdep_init_map);
+
+struct lock_class_key __lockdep_no_validate__;
+EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
+
+static int
+print_lock_nested_lock_not_held(struct task_struct *curr,
+                                struct held_lock *hlock,
+                                unsigned long ip)
+{
+        if (!debug_locks_off())
+                return 0;
+        if (debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("==================================\n");
+        printk("[ BUG: Nested lock was not taken ]\n");
+        print_kernel_ident();
+        printk("----------------------------------\n");
+
+        printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
+        print_lock(hlock);
+
+        printk("\nbut this task is not holding:\n");
+        printk("%s\n", hlock->nest_lock->name);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        printk("\nother info that might help us debug this:\n");
+        lockdep_print_held_locks(curr);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+static int __lock_is_held(struct lockdep_map *lock);
+
+/*
+ * This gets called for every mutex_lock*()/spin_lock*() operation.
+ * We maintain the dependency maps and validate the locking attempt:
+ */
+static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
+                          int trylock, int read, int check, int hardirqs_off,
+                          struct lockdep_map *nest_lock, unsigned long ip,
+                          int references)
+{
+        struct task_struct *curr = current;
+        struct lock_class *class = NULL;
+        struct held_lock *hlock;
+        unsigned int depth, id;
+        int chain_head = 0;
+        int class_idx;
+        u64 chain_key;
+
+        if (!prove_locking)
+                check = 1;
+
+        if (unlikely(!debug_locks))
+                return 0;
+
+        /*
+         * Lockdep should run with IRQs disabled, otherwise we could
+         * get an interrupt which would want to take locks, which would
+         * end up in lockdep and have you got a head-ache already?
+         */
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return 0;
+
+        if (lock->key == &__lockdep_no_validate__)
+                check = 1;
+
+        if (subclass < NR_LOCKDEP_CACHING_CLASSES)
+                class = lock->class_cache[subclass];
+        /*
+         * Not cached?
+         */
+        if (unlikely(!class)) {
+                class = register_lock_class(lock, subclass, 0);
+                if (!class)
+                        return 0;
+        }
+        atomic_inc((atomic_t *)&class->ops);
+        if (very_verbose(class)) {
+                printk("\nacquire class [%p] %s", class->key, class->name);
+                if (class->name_version > 1)
+                        printk("#%d", class->name_version);
+                printk("\n");
+                dump_stack();
+        }
+
+        /*
+         * Add the lock to the list of currently held locks.
+         * (we dont increase the depth just yet, up until the
+         * dependency checks are done)
+         */
+        depth = curr->lockdep_depth;
+        /*
+         * Ran out of static storage for our per-task lock stack again have we?
+         */
+        if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
+                return 0;
+
+        class_idx = class - lock_classes + 1;
+
+        if (depth) {
+                hlock = curr->held_locks + depth - 1;
+                if (hlock->class_idx == class_idx && nest_lock) {
+                        if (hlock->references)
+                                hlock->references++;
+                        else
+                                hlock->references = 2;
+
+                        return 1;
+                }
+        }
+
+        hlock = curr->held_locks + depth;
+        /*
+         * Plain impossible, we just registered it and checked it weren't no
+         * NULL like.. I bet this mushroom I ate was good!
+         */
+        if (DEBUG_LOCKS_WARN_ON(!class))
+                return 0;
+        hlock->class_idx = class_idx;
+        hlock->acquire_ip = ip;
+        hlock->instance = lock;
+        hlock->nest_lock = nest_lock;
+        hlock->trylock = trylock;
+        hlock->read = read;
+        hlock->check = check;
+        hlock->hardirqs_off = !!hardirqs_off;
+        hlock->references = references;
+#ifdef CONFIG_LOCK_STAT
+        hlock->waittime_stamp = 0;
+        hlock->holdtime_stamp = lockstat_clock();
+#endif
+
+        if (check == 2 && !mark_irqflags(curr, hlock))
+                return 0;
+
+        /* mark it as used: */
+        if (!mark_lock(curr, hlock, LOCK_USED))
+                return 0;
+
+        /*
+         * Calculate the chain hash: it's the combined hash of all the
+         * lock keys along the dependency chain. We save the hash value
+         * at every step so that we can get the current hash easily
+         * after unlock. The chain hash is then used to cache dependency
+         * results.
+         *
+         * The 'key ID' is what is the most compact key value to drive
+         * the hash, not class->key.
+         */
+        id = class - lock_classes;
+        /*
+         * Whoops, we did it again.. ran straight out of our static allocation.
+         */
+        if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+                return 0;
+
+        chain_key = curr->curr_chain_key;
+        if (!depth) {
+                /*
+                 * How can we have a chain hash when we ain't got no keys?!
+                 */
+                if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
+                        return 0;
+                chain_head = 1;
+        }
+
+        hlock->prev_chain_key = chain_key;
+        if (separate_irq_context(curr, hlock)) {
+                chain_key = 0;
+                chain_head = 1;
+        }
+        chain_key = iterate_chain_key(chain_key, id);
+
+        if (nest_lock && !__lock_is_held(nest_lock))
+                return print_lock_nested_lock_not_held(curr, hlock, ip);
+
+        if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
+                return 0;
+
+        curr->curr_chain_key = chain_key;
+        curr->lockdep_depth++;
+        check_chain_key(curr);
+#ifdef CONFIG_DEBUG_LOCKDEP
+        if (unlikely(!debug_locks))
+                return 0;
+#endif
+        if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
+                debug_locks_off();
+                print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
+                printk(KERN_DEBUG "depth: %i  max: %lu!\n",
+                       curr->lockdep_depth, MAX_LOCK_DEPTH);
+
+                lockdep_print_held_locks(current);
+                debug_show_all_locks();
+                dump_stack();
+
+                return 0;
+        }
+
+        if (unlikely(curr->lockdep_depth > max_lockdep_depth))
+                max_lockdep_depth = curr->lockdep_depth;
+
+        return 1;
+}
+
+static int
+print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
+                           unsigned long ip)
+{
+        if (!debug_locks_off())
+                return 0;
+        if (debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("=====================================\n");
+        printk("[ BUG: bad unlock balance detected! ]\n");
+        print_kernel_ident();
+        printk("-------------------------------------\n");
+        printk("%s/%d is trying to release lock (",
+                curr->comm, task_pid_nr(curr));
+        print_lockdep_cache(lock);
+        printk(") at:\n");
+        print_ip_sym(ip);
+        printk("but there are no more locks to release!\n");
+        printk("\nother info that might help us debug this:\n");
+        lockdep_print_held_locks(curr);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+/*
+ * Common debugging checks for both nested and non-nested unlock:
+ */
+static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
+                        unsigned long ip)
+{
+        if (unlikely(!debug_locks))
+                return 0;
+        /*
+         * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
+         */
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return 0;
+
+        if (curr->lockdep_depth <= 0)
+                return print_unlock_imbalance_bug(curr, lock, ip);
+
+        return 1;
+}
+
+static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
+{
+        if (hlock->instance == lock)
+                return 1;
+
+        if (hlock->references) {
+                struct lock_class *class = lock->class_cache[0];
+
+                if (!class)
+                        class = look_up_lock_class(lock, 0);
+
+                /*
+                 * If look_up_lock_class() failed to find a class, we're trying
+                 * to test if we hold a lock that has never yet been acquired.
+                 * Clearly if the lock hasn't been acquired _ever_, we're not
+                 * holding it either, so report failure.
+                 */
+                if (!class)
+                        return 0;
+
+                /*
+                 * References, but not a lock we're actually ref-counting?
+                 * State got messed up, follow the sites that change ->references
+                 * and try to make sense of it.
+                 */
+                if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
+                        return 0;
+
+                if (hlock->class_idx == class - lock_classes + 1)
+                        return 1;
+        }
+
+        return 0;
+}
+
+static int
+__lock_set_class(struct lockdep_map *lock, const char *name,
+                 struct lock_class_key *key, unsigned int subclass,
+                 unsigned long ip)
+{
+        struct task_struct *curr = current;
+        struct held_lock *hlock, *prev_hlock;
+        struct lock_class *class;
+        unsigned int depth;
+        int i;
+
+        depth = curr->lockdep_depth;
+        /*
+         * This function is about (re)setting the class of a held lock,
+         * yet we're not actually holding any locks. Naughty user!
+         */
+        if (DEBUG_LOCKS_WARN_ON(!depth))
+                return 0;
+
+        prev_hlock = NULL;
+        for (i = depth-1; i >= 0; i--) {
+                hlock = curr->held_locks + i;
+                /*
+                 * We must not cross into another context:
+                 */
+                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+                        break;
+                if (match_held_lock(hlock, lock))
+                        goto found_it;
+                prev_hlock = hlock;
+        }
+        return print_unlock_imbalance_bug(curr, lock, ip);
+
+found_it:
+        lockdep_init_map(lock, name, key, 0);
+        class = register_lock_class(lock, subclass, 0);
+        hlock->class_idx = class - lock_classes + 1;
+
+        curr->lockdep_depth = i;
+        curr->curr_chain_key = hlock->prev_chain_key;
+
+        for (; i < depth; i++) {
+                hlock = curr->held_locks + i;
+                if (!__lock_acquire(hlock->instance,
+                        hlock_class(hlock)->subclass, hlock->trylock,
+                                hlock->read, hlock->check, hlock->hardirqs_off,
+                                hlock->nest_lock, hlock->acquire_ip,
+                                hlock->references))
+                        return 0;
+        }
+
+        /*
+         * I took it apart and put it back together again, except now I have
+         * these 'spare' parts.. where shall I put them.
+         */
+        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
+                return 0;
+        return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks in a
+ * potentially non-nested (out of order) manner. This is a
+ * relatively rare operation, as all the unlock APIs default
+ * to nested mode (which uses lock_release()):
+ */
+static int
+lock_release_non_nested(struct task_struct *curr,
+                        struct lockdep_map *lock, unsigned long ip)
+{
+        struct held_lock *hlock, *prev_hlock;
+        unsigned int depth;
+        int i;
+
+        /*
+         * Check whether the lock exists in the current stack
+         * of held locks:
+         */
+        depth = curr->lockdep_depth;
+        /*
+         * So we're all set to release this lock.. wait what lock? We don't
+         * own any locks, you've been drinking again?
+         */
+        if (DEBUG_LOCKS_WARN_ON(!depth))
+                return 0;
+
+        prev_hlock = NULL;
+        for (i = depth-1; i >= 0; i--) {
+                hlock = curr->held_locks + i;
+                /*
+                 * We must not cross into another context:
+                 */
+                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+                        break;
+                if (match_held_lock(hlock, lock))
+                        goto found_it;
+                prev_hlock = hlock;
+        }
+        return print_unlock_imbalance_bug(curr, lock, ip);
+
+found_it:
+        if (hlock->instance == lock)
+                lock_release_holdtime(hlock);
+
+        if (hlock->references) {
+                hlock->references--;
+                if (hlock->references) {
+                        /*
+                         * We had, and after removing one, still have
+                         * references, the current lock stack is still
+                         * valid. We're done!
+                         */
+                        return 1;
+                }
+        }
+
+        /*
+         * We have the right lock to unlock, 'hlock' points to it.
+         * Now we remove it from the stack, and add back the other
+         * entries (if any), recalculating the hash along the way:
+         */
+
+        curr->lockdep_depth = i;
+        curr->curr_chain_key = hlock->prev_chain_key;
+
+        for (i++; i < depth; i++) {
+                hlock = curr->held_locks + i;
+                if (!__lock_acquire(hlock->instance,
+                        hlock_class(hlock)->subclass, hlock->trylock,
+                                hlock->read, hlock->check, hlock->hardirqs_off,
+                                hlock->nest_lock, hlock->acquire_ip,
+                                hlock->references))
+                        return 0;
+        }
+
+        /*
+         * We had N bottles of beer on the wall, we drank one, but now
+         * there's not N-1 bottles of beer left on the wall...
+         */
+        if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
+                return 0;
+        return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks - this gets
+ * called on mutex_unlock()/spin_unlock*() (or on a failed
+ * mutex_lock_interruptible()). This is done for unlocks that nest
+ * perfectly. (i.e. the current top of the lock-stack is unlocked)
+ */
+static int lock_release_nested(struct task_struct *curr,
+                               struct lockdep_map *lock, unsigned long ip)
+{
+        struct held_lock *hlock;
+        unsigned int depth;
+
+        /*
+         * Pop off the top of the lock stack:
+         */
+        depth = curr->lockdep_depth - 1;
+        hlock = curr->held_locks + depth;
+
+        /*
+         * Is the unlock non-nested:
+         */
+        if (hlock->instance != lock || hlock->references)
+                return lock_release_non_nested(curr, lock, ip);
+        curr->lockdep_depth--;
+
+        /*
+         * No more locks, but somehow we've got hash left over, who left it?
+         */
+        if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
+                return 0;
+
+        curr->curr_chain_key = hlock->prev_chain_key;
+
+        lock_release_holdtime(hlock);
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+        hlock->prev_chain_key = 0;
+        hlock->class_idx = 0;
+        hlock->acquire_ip = 0;
+        hlock->irq_context = 0;
+#endif
+        return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks - this gets
+ * called on mutex_unlock()/spin_unlock*() (or on a failed
+ * mutex_lock_interruptible()). This is done for unlocks that nest
+ * perfectly. (i.e. the current top of the lock-stack is unlocked)
+ */
+static void
+__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
+{
+        struct task_struct *curr = current;
+
+        if (!check_unlock(curr, lock, ip))
+                return;
+
+        if (nested) {
+                if (!lock_release_nested(curr, lock, ip))
+                        return;
+        } else {
+                if (!lock_release_non_nested(curr, lock, ip))
+                        return;
+        }
+
+        check_chain_key(curr);
+}
+
+static int __lock_is_held(struct lockdep_map *lock)
+{
+        struct task_struct *curr = current;
+        int i;
+
+        for (i = 0; i < curr->lockdep_depth; i++) {
+                struct held_lock *hlock = curr->held_locks + i;
+
+                if (match_held_lock(hlock, lock))
+                        return 1;
+        }
+
+        return 0;
+}
+
+/*
+ * Check whether we follow the irq-flags state precisely:
+ */
+static void check_flags(unsigned long flags)
+{
+#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
+    defined(CONFIG_TRACE_IRQFLAGS)
+        if (!debug_locks)
+                return;
+
+        if (irqs_disabled_flags(flags)) {
+                if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
+                        printk("possible reason: unannotated irqs-off.\n");
+                }
+        } else {
+                if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
+                        printk("possible reason: unannotated irqs-on.\n");
+                }
+        }
+
+        /*
+         * We dont accurately track softirq state in e.g.
+         * hardirq contexts (such as on 4KSTACKS), so only
+         * check if not in hardirq contexts:
+         */
+        if (!hardirq_count()) {
+                if (softirq_count()) {
+                        /* like the above, but with softirqs */
+                        DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
+                } else {
+                        /* lick the above, does it taste good? */
+                        DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
+                }
+        }
+
+        if (!debug_locks)
+                print_irqtrace_events(current);
+#endif
+}
+
+void lock_set_class(struct lockdep_map *lock, const char *name,
+                    struct lock_class_key *key, unsigned int subclass,
+                    unsigned long ip)
+{
+        unsigned long flags;
+
+        if (unlikely(current->lockdep_recursion))
+                return;
+
+        raw_local_irq_save(flags);
+        current->lockdep_recursion = 1;
+        check_flags(flags);
+        if (__lock_set_class(lock, name, key, subclass, ip))
+                check_chain_key(current);
+        current->lockdep_recursion = 0;
+        raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_set_class);
+
+/*
+ * We are not always called with irqs disabled - do that here,
+ * and also avoid lockdep recursion:
+ */
+void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
+                          int trylock, int read, int check,
+                          struct lockdep_map *nest_lock, unsigned long ip)
+{
+        unsigned long flags;
+
+        if (unlikely(current->lockdep_recursion))
+                return;
+
+        raw_local_irq_save(flags);
+        check_flags(flags);
+
+        current->lockdep_recursion = 1;
+        trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
+        __lock_acquire(lock, subclass, trylock, read, check,
+                       irqs_disabled_flags(flags), nest_lock, ip, 0);
+        current->lockdep_recursion = 0;
+        raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_acquire);
+
+void lock_release(struct lockdep_map *lock, int nested,
+                          unsigned long ip)
+{
+        unsigned long flags;
+
+        if (unlikely(current->lockdep_recursion))
+                return;
+
+        raw_local_irq_save(flags);
+        check_flags(flags);
+        current->lockdep_recursion = 1;
+        trace_lock_release(lock, ip);
+        __lock_release(lock, nested, ip);
+        current->lockdep_recursion = 0;
+        raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_release);
+
+int lock_is_held(struct lockdep_map *lock)
+{
+        unsigned long flags;
+        int ret = 0;
+
+        if (unlikely(current->lockdep_recursion))
+                return 1; /* avoid false negative lockdep_assert_held() */
+
+        raw_local_irq_save(flags);
+        check_flags(flags);
+
+        current->lockdep_recursion = 1;
+        ret = __lock_is_held(lock);
+        current->lockdep_recursion = 0;
+        raw_local_irq_restore(flags);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(lock_is_held);
+
+void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
+{
+        current->lockdep_reclaim_gfp = gfp_mask;
+}
+
+void lockdep_clear_current_reclaim_state(void)
+{
+        current->lockdep_reclaim_gfp = 0;
+}
+
+#ifdef CONFIG_LOCK_STAT
+static int
+print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
+                           unsigned long ip)
+{
+        if (!debug_locks_off())
+                return 0;
+        if (debug_locks_silent)
+                return 0;
+
+        printk("\n");
+        printk("=================================\n");
+        printk("[ BUG: bad contention detected! ]\n");
+        print_kernel_ident();
+        printk("---------------------------------\n");
+        printk("%s/%d is trying to contend lock (",
+                curr->comm, task_pid_nr(curr));
+        print_lockdep_cache(lock);
+        printk(") at:\n");
+        print_ip_sym(ip);
+        printk("but there are no locks held!\n");
+        printk("\nother info that might help us debug this:\n");
+        lockdep_print_held_locks(curr);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+
+        return 0;
+}
+
+static void
+__lock_contended(struct lockdep_map *lock, unsigned long ip)
+{
+        struct task_struct *curr = current;
+        struct held_lock *hlock, *prev_hlock;
+        struct lock_class_stats *stats;
+        unsigned int depth;
+        int i, contention_point, contending_point;
+
+        depth = curr->lockdep_depth;
+        /*
+         * Whee, we contended on this lock, except it seems we're not
+         * actually trying to acquire anything much at all..
+         */
+        if (DEBUG_LOCKS_WARN_ON(!depth))
+                return;
+
+        prev_hlock = NULL;
+        for (i = depth-1; i >= 0; i--) {
+                hlock = curr->held_locks + i;
+                /*
+                 * We must not cross into another context:
+                 */
+                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+                        break;
+                if (match_held_lock(hlock, lock))
+                        goto found_it;
+                prev_hlock = hlock;
+        }
+        print_lock_contention_bug(curr, lock, ip);
+        return;
+
+found_it:
+        if (hlock->instance != lock)
+                return;
+
+        hlock->waittime_stamp = lockstat_clock();
+
+        contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
+        contending_point = lock_point(hlock_class(hlock)->contending_point,
+                                      lock->ip);
+
+        stats = get_lock_stats(hlock_class(hlock));
+        if (contention_point < LOCKSTAT_POINTS)
+                stats->contention_point[contention_point]++;
+        if (contending_point < LOCKSTAT_POINTS)
+                stats->contending_point[contending_point]++;
+        if (lock->cpu != smp_processor_id())
+                stats->bounces[bounce_contended + !!hlock->read]++;
+        put_lock_stats(stats);
+}
+
+static void
+__lock_acquired(struct lockdep_map *lock, unsigned long ip)
+{
+        struct task_struct *curr = current;
+        struct held_lock *hlock, *prev_hlock;
+        struct lock_class_stats *stats;
+        unsigned int depth;
+        u64 now, waittime = 0;
+        int i, cpu;
+
+        depth = curr->lockdep_depth;
+        /*
+         * Yay, we acquired ownership of this lock we didn't try to
+         * acquire, how the heck did that happen?
+         */
+        if (DEBUG_LOCKS_WARN_ON(!depth))
+                return;
+
+        prev_hlock = NULL;
+        for (i = depth-1; i >= 0; i--) {
+                hlock = curr->held_locks + i;
+                /*
+                 * We must not cross into another context:
+                 */
+                if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+                        break;
+                if (match_held_lock(hlock, lock))
+                        goto found_it;
+                prev_hlock = hlock;
+        }
+        print_lock_contention_bug(curr, lock, _RET_IP_);
+        return;
+
+found_it:
+        if (hlock->instance != lock)
+                return;
+
+        cpu = smp_processor_id();
+        if (hlock->waittime_stamp) {
+                now = lockstat_clock();
+                waittime = now - hlock->waittime_stamp;
+                hlock->holdtime_stamp = now;
+        }
+
+        trace_lock_acquired(lock, ip);
+
+        stats = get_lock_stats(hlock_class(hlock));
+        if (waittime) {
+                if (hlock->read)
+                        lock_time_inc(&stats->read_waittime, waittime);
+                else
+                        lock_time_inc(&stats->write_waittime, waittime);
+        }
+        if (lock->cpu != cpu)
+                stats->bounces[bounce_acquired + !!hlock->read]++;
+        put_lock_stats(stats);
+
+        lock->cpu = cpu;
+        lock->ip = ip;
+}
+
+void lock_contended(struct lockdep_map *lock, unsigned long ip)
+{
+        unsigned long flags;
+
+        if (unlikely(!lock_stat))
+                return;
+
+        if (unlikely(current->lockdep_recursion))
+                return;
+
+        raw_local_irq_save(flags);
+        check_flags(flags);
+        current->lockdep_recursion = 1;
+        trace_lock_contended(lock, ip);
+        __lock_contended(lock, ip);
+        current->lockdep_recursion = 0;
+        raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_contended);
+
+void lock_acquired(struct lockdep_map *lock, unsigned long ip)
+{
+        unsigned long flags;
+
+        if (unlikely(!lock_stat))
+                return;
+
+        if (unlikely(current->lockdep_recursion))
+                return;
+
+        raw_local_irq_save(flags);
+        check_flags(flags);
+        current->lockdep_recursion = 1;
+        __lock_acquired(lock, ip);
+        current->lockdep_recursion = 0;
+        raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_acquired);
+#endif
+
+/*
+ * Used by the testsuite, sanitize the validator state
+ * after a simulated failure:
+ */
+
+void lockdep_reset(void)
+{
+        unsigned long flags;
+        int i;
+
+        raw_local_irq_save(flags);
+        current->curr_chain_key = 0;
+        current->lockdep_depth = 0;
+        current->lockdep_recursion = 0;
+        memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
+        nr_hardirq_chains = 0;
+        nr_softirq_chains = 0;
+        nr_process_chains = 0;
+        debug_locks = 1;
+        for (i = 0; i < CHAINHASH_SIZE; i++)
+                INIT_LIST_HEAD(chainhash_table + i);
+        raw_local_irq_restore(flags);
+}
+
+static void zap_class(struct lock_class *class)
+{
+        int i;
+
+        /*
+         * Remove all dependencies this lock is
+         * involved in:
+         */
+        for (i = 0; i < nr_list_entries; i++) {
+                if (list_entries[i].class == class)
+                        list_del_rcu(&list_entries[i].entry);
+        }
+        /*
+         * Unhash the class and remove it from the all_lock_classes list:
+         */
+        list_del_rcu(&class->hash_entry);
+        list_del_rcu(&class->lock_entry);
+
+        class->key = NULL;
+}
+
+static inline int within(const void *addr, void *start, unsigned long size)
+{
+        return addr >= start && addr < start + size;
+}
+
+void lockdep_free_key_range(void *start, unsigned long size)
+{
+        struct lock_class *class, *next;
+        struct list_head *head;
+        unsigned long flags;
+        int i;
+        int locked;
+
+        raw_local_irq_save(flags);
+        locked = graph_lock();
+
+        /*
+         * Unhash all classes that were created by this module:
+         */
+        for (i = 0; i < CLASSHASH_SIZE; i++) {
+                head = classhash_table + i;
+                if (list_empty(head))
+                        continue;
+                list_for_each_entry_safe(class, next, head, hash_entry) {
+                        if (within(class->key, start, size))
+                                zap_class(class);
+                        else if (within(class->name, start, size))
+                                zap_class(class);
+                }
+        }
+
+        if (locked)
+                graph_unlock();
+        raw_local_irq_restore(flags);
+}
+
+void lockdep_reset_lock(struct lockdep_map *lock)
+{
+        struct lock_class *class, *next;
+        struct list_head *head;
+        unsigned long flags;
+        int i, j;
+        int locked;
+
+        raw_local_irq_save(flags);
+
+        /*
+         * Remove all classes this lock might have:
+         */
+        for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
+                /*
+                 * If the class exists we look it up and zap it:
+                 */
+                class = look_up_lock_class(lock, j);
+                if (class)
+                        zap_class(class);
+        }
+        /*
+         * Debug check: in the end all mapped classes should
+         * be gone.
+         */
+        locked = graph_lock();
+        for (i = 0; i < CLASSHASH_SIZE; i++) {
+                head = classhash_table + i;
+                if (list_empty(head))
+                        continue;
+                list_for_each_entry_safe(class, next, head, hash_entry) {
+                        int match = 0;
+
+                        for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
+                                match |= class == lock->class_cache[j];
+
+                        if (unlikely(match)) {
+                                if (debug_locks_off_graph_unlock()) {
+                                        /*
+                                         * We all just reset everything, how did it match?
+                                         */
+                                        WARN_ON(1);
+                                }
+                                goto out_restore;
+                        }
+                }
+        }
+        if (locked)
+                graph_unlock();
+
+out_restore:
+        raw_local_irq_restore(flags);
+}
+
+void lockdep_init(void)
+{
+        int i;
+
+        /*
+         * Some architectures have their own start_kernel()
+         * code which calls lockdep_init(), while we also
+         * call lockdep_init() from the start_kernel() itself,
+         * and we want to initialize the hashes only once:
+         */
+        if (lockdep_initialized)
+                return;
+
+        for (i = 0; i < CLASSHASH_SIZE; i++)
+                INIT_LIST_HEAD(classhash_table + i);
+
+        for (i = 0; i < CHAINHASH_SIZE; i++)
+                INIT_LIST_HEAD(chainhash_table + i);
+
+        lockdep_initialized = 1;
+}
+
+void __init lockdep_info(void)
+{
+        printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
+
+        printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
+        printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
+        printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
+        printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
+        printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
+        printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
+        printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
+
+        printk(" memory used by lock dependency info: %lu kB\n",
+                (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
+                sizeof(struct list_head) * CLASSHASH_SIZE +
+                sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
+                sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
+                sizeof(struct list_head) * CHAINHASH_SIZE
+#ifdef CONFIG_PROVE_LOCKING
+                + sizeof(struct circular_queue)
+#endif
+                ) / 1024
+                );
+
+        printk(" per task-struct memory footprint: %lu bytes\n",
+                sizeof(struct held_lock) * MAX_LOCK_DEPTH);
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+        if (lockdep_init_error) {
+                printk("WARNING: lockdep init error! lock-%s was acquired"
+                        "before lockdep_init\n", lock_init_error);
+                printk("Call stack leading to lockdep invocation was:\n");
+                print_stack_trace(&lockdep_init_trace, 0);
+        }
+#endif
+}
+
+static void
+print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
+                     const void *mem_to, struct held_lock *hlock)
+{
+        if (!debug_locks_off())
+                return;
+        if (debug_locks_silent)
+                return;
+
+        printk("\n");
+        printk("=========================\n");
+        printk("[ BUG: held lock freed! ]\n");
+        print_kernel_ident();
+        printk("-------------------------\n");
+        printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
+                curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
+        print_lock(hlock);
+        lockdep_print_held_locks(curr);
+
+        printk("\nstack backtrace:\n");
+        dump_stack();
+}
+
+static inline int not_in_range(const void* mem_from, unsigned long mem_len,
+                                const void* lock_from, unsigned long lock_len)
+{
+        return lock_from + lock_len <= mem_from ||
+                mem_from + mem_len <= lock_from;
+}
+
+/*
+ * Called when kernel memory is freed (or unmapped), or if a lock
+ * is destroyed or reinitialized - this code checks whether there is
+ * any held lock in the memory range of <from> to <to>:
+ */
+void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
+{
+        struct task_struct *curr = current;
+        struct held_lock *hlock;
+        unsigned long flags;
+        int i;
+
+        if (unlikely(!debug_locks))
+                return;
+
+        local_irq_save(flags);
+        for (i = 0; i < curr->lockdep_depth; i++) {
+                hlock = curr->held_locks + i;
+
+                if (not_in_range(mem_from, mem_len, hlock->instance,
+                                        sizeof(*hlock->instance)))
+                        continue;
+
+                print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
+                break;
+        }
+        local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
+
+static void print_held_locks_bug(void)
+{
+        if (!debug_locks_off())
+                return;
+        if (debug_locks_silent)
+                return;
+
+        printk("\n");
+        printk("=====================================\n");
+        printk("[ BUG: %s/%d still has locks held! ]\n",
+               current->comm, task_pid_nr(current));
+        print_kernel_ident();
+        printk("-------------------------------------\n");
+        lockdep_print_held_locks(current);
+        printk("\nstack backtrace:\n");
+        dump_stack();
+}
+
+void debug_check_no_locks_held(void)
+{
+        if (unlikely(current->lockdep_depth > 0))
+                print_held_locks_bug();
+}
+EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
+
+void debug_show_all_locks(void)
+{
+        struct task_struct *g, *p;
+        int count = 10;
+        int unlock = 1;
+
+        if (unlikely(!debug_locks)) {
+                printk("INFO: lockdep is turned off.\n");
+                return;
+        }
+        printk("\nShowing all locks held in the system:\n");
+
+        /*
+         * Here we try to get the tasklist_lock as hard as possible,
+         * if not successful after 2 seconds we ignore it (but keep
+         * trying). This is to enable a debug printout even if a
+         * tasklist_lock-holding task deadlocks or crashes.
+         */
+retry:
+        if (!read_trylock(&tasklist_lock)) {
+                if (count == 10)
+                        printk("hm, tasklist_lock locked, retrying... ");
+                if (count) {
+                        count--;
+                        printk(" #%d", 10-count);
+                        mdelay(200);
+                        goto retry;
+                }
+                printk(" ignoring it.\n");
+                unlock = 0;
+        } else {
+                if (count != 10)
+                        printk(KERN_CONT " locked it.\n");
+        }
+
+        do_each_thread(g, p) {
+                /*
+                 * It's not reliable to print a task's held locks
+                 * if it's not sleeping (or if it's not the current
+                 * task):
+                 */
+                if (p->state == TASK_RUNNING && p != current)
+                        continue;
+                if (p->lockdep_depth)
+                        lockdep_print_held_locks(p);
+                if (!unlock)
+                        if (read_trylock(&tasklist_lock))
+                                unlock = 1;
+        } while_each_thread(g, p);
+
+        printk("\n");
+        printk("=============================================\n\n");
+
+        if (unlock)
+                read_unlock(&tasklist_lock);
+}
+EXPORT_SYMBOL_GPL(debug_show_all_locks);
+
+/*
+ * Careful: only use this function if you are sure that
+ * the task cannot run in parallel!
+ */
+void debug_show_held_locks(struct task_struct *task)
+{
+        if (unlikely(!debug_locks)) {
+                printk("INFO: lockdep is turned off.\n");
+                return;
+        }
+        lockdep_print_held_locks(task);
+}
+EXPORT_SYMBOL_GPL(debug_show_held_locks);
+
+void lockdep_sys_exit(void)
+{
+        struct task_struct *curr = current;
+
+        if (unlikely(curr->lockdep_depth)) {
+                if (!debug_locks_off())
+                        return;
+                printk("\n");
+                printk("================================================\n");
+                printk("[ BUG: lock held when returning to user space! ]\n");
+                print_kernel_ident();
+                printk("------------------------------------------------\n");
+                printk("%s/%d is leaving the kernel with locks still held!\n",
+                                curr->comm, curr->pid);
+                lockdep_print_held_locks(curr);
+        }
+}
+
+void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
+{
+        struct task_struct *curr = current;
+
+#ifndef CONFIG_PROVE_RCU_REPEATEDLY
+        if (!debug_locks_off())
+                return;
+#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
+        /* Note: the following can be executed concurrently, so be careful. */
+        printk("\n");
+        printk("===============================\n");
+        printk("[ INFO: suspicious RCU usage. ]\n");
+        print_kernel_ident();
+        printk("-------------------------------\n");
+        printk("%s:%d %s!\n", file, line, s);
+        printk("\nother info that might help us debug this:\n\n");
+        printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
+               !rcu_lockdep_current_cpu_online()
+                        ? "RCU used illegally from offline CPU!\n"
+                        : !rcu_is_watching()
+                                ? "RCU used illegally from idle CPU!\n"
+                                : "",
+               rcu_scheduler_active, debug_locks);
+
+        /*
+         * If a CPU is in the RCU-free window in idle (ie: in the section
+         * between rcu_idle_enter() and rcu_idle_exit(), then RCU
+         * considers that CPU to be in an "extended quiescent state",
+         * which means that RCU will be completely ignoring that CPU.
+         * Therefore, rcu_read_lock() and friends have absolutely no
+         * effect on a CPU running in that state. In other words, even if
+         * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
+         * delete data structures out from under it.  RCU really has no
+         * choice here: we need to keep an RCU-free window in idle where
+         * the CPU may possibly enter into low power mode. This way we can
+         * notice an extended quiescent state to other CPUs that started a grace
+         * period. Otherwise we would delay any grace period as long as we run
+         * in the idle task.
+         *
+         * So complain bitterly if someone does call rcu_read_lock(),
+         * rcu_read_lock_bh() and so on from extended quiescent states.
+         */
+        if (!rcu_is_watching())
+                printk("RCU used illegally from extended quiescent state!\n");
+
+        lockdep_print_held_locks(curr);
+        printk("\nstack backtrace:\n");
+        dump_stack();
+}
+EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
new file mode 100644
index 000000000000..4f560cfedc8f
--- /dev/null
+++ b/kernel/locking/lockdep_internals.h
@@ -0,0 +1,170 @@
+/*
+ * kernel/lockdep_internals.h
+ *
+ * Runtime locking correctness validator
+ *
+ * lockdep subsystem internal functions and variables.
+ */
+
+/*
+ * Lock-class usage-state bits:
+ */
+enum lock_usage_bit {
+#define LOCKDEP_STATE(__STATE)          \
+        LOCK_USED_IN_##__STATE,         \
+        LOCK_USED_IN_##__STATE##_READ,  \
+        LOCK_ENABLED_##__STATE,         \
+        LOCK_ENABLED_##__STATE##_READ,
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+        LOCK_USED,
+        LOCK_USAGE_STATES
+};
+
+/*
+ * Usage-state bitmasks:
+ */
+#define __LOCKF(__STATE)        LOCKF_##__STATE = (1 << LOCK_##__STATE),
+
+enum {
+#define LOCKDEP_STATE(__STATE)                                          \
+        __LOCKF(USED_IN_##__STATE)                                      \
+        __LOCKF(USED_IN_##__STATE##_READ)                               \
+        __LOCKF(ENABLED_##__STATE)                                      \
+        __LOCKF(ENABLED_##__STATE##_READ)
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+        __LOCKF(USED)
+};
+
+#define LOCKF_ENABLED_IRQ (LOCKF_ENABLED_HARDIRQ | LOCKF_ENABLED_SOFTIRQ)
+#define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
+
+#define LOCKF_ENABLED_IRQ_READ \
+                (LOCKF_ENABLED_HARDIRQ_READ | LOCKF_ENABLED_SOFTIRQ_READ)
+#define LOCKF_USED_IN_IRQ_READ \
+                (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
+
+/*
+ * MAX_LOCKDEP_ENTRIES is the maximum number of lock dependencies
+ * we track.
+ *
+ * We use the per-lock dependency maps in two ways: we grow it by adding
+ * every to-be-taken lock to all currently held lock's own dependency
+ * table (if it's not there yet), and we check it for lock order
+ * conflicts and deadlocks.
+ */
+#define MAX_LOCKDEP_ENTRIES     16384UL
+
+#define MAX_LOCKDEP_CHAINS_BITS 15
+#define MAX_LOCKDEP_CHAINS      (1UL << MAX_LOCKDEP_CHAINS_BITS)
+
+#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
+
+/*
+ * Stack-trace: tightly packed array of stack backtrace
+ * addresses. Protected by the hash_lock.
+ */
+#define MAX_STACK_TRACE_ENTRIES 262144UL
+
+extern struct list_head all_lock_classes;
+extern struct lock_chain lock_chains[];
+
+#define LOCK_USAGE_CHARS (1+LOCK_USAGE_STATES/2)
+
+extern void get_usage_chars(struct lock_class *class,
+                            char usage[LOCK_USAGE_CHARS]);
+
+extern const char * __get_key_name(struct lockdep_subclass_key *key, char *str);
+
+struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i);
+
+extern unsigned long nr_lock_classes;
+extern unsigned long nr_list_entries;
+extern unsigned long nr_lock_chains;
+extern int nr_chain_hlocks;
+extern unsigned long nr_stack_trace_entries;
+
+extern unsigned int nr_hardirq_chains;
+extern unsigned int nr_softirq_chains;
+extern unsigned int nr_process_chains;
+extern unsigned int max_lockdep_depth;
+extern unsigned int max_recursion_depth;
+
+extern unsigned int max_bfs_queue_depth;
+
+#ifdef CONFIG_PROVE_LOCKING
+extern unsigned long lockdep_count_forward_deps(struct lock_class *);
+extern unsigned long lockdep_count_backward_deps(struct lock_class *);
+#else
+static inline unsigned long
+lockdep_count_forward_deps(struct lock_class *class)
+{
+        return 0;
+}
+static inline unsigned long
+lockdep_count_backward_deps(struct lock_class *class)
+{
+        return 0;
+}
+#endif
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+
+#include <asm/local.h>
+/*
+ * Various lockdep statistics.
+ * We want them per cpu as they are often accessed in fast path
+ * and we want to avoid too much cache bouncing.
+ */
+struct lockdep_stats {
+        int     chain_lookup_hits;
+        int     chain_lookup_misses;
+        int     hardirqs_on_events;
+        int     hardirqs_off_events;
+        int     redundant_hardirqs_on;
+        int     redundant_hardirqs_off;
+        int     softirqs_on_events;
+        int     softirqs_off_events;
+        int     redundant_softirqs_on;
+        int     redundant_softirqs_off;
+        int     nr_unused_locks;
+        int     nr_cyclic_checks;
+        int     nr_cyclic_check_recursions;
+        int     nr_find_usage_forwards_checks;
+        int     nr_find_usage_forwards_recursions;
+        int     nr_find_usage_backwards_checks;
+        int     nr_find_usage_backwards_recursions;
+};
+
+DECLARE_PER_CPU(struct lockdep_stats, lockdep_stats);
+
+#define __debug_atomic_inc(ptr)                                 \
+        this_cpu_inc(lockdep_stats.ptr);
+
+#define debug_atomic_inc(ptr)                   {               \
+        WARN_ON_ONCE(!irqs_disabled());                         \
+        __this_cpu_inc(lockdep_stats.ptr);                      \
+}
+
+#define debug_atomic_dec(ptr)                   {               \
+        WARN_ON_ONCE(!irqs_disabled());                         \
+        __this_cpu_dec(lockdep_stats.ptr);                      \
+}
+
+#define debug_atomic_read(ptr)          ({                              \
+        struct lockdep_stats *__cpu_lockdep_stats;                      \
+        unsigned long long __total = 0;                                 \
+        int __cpu;                                                      \
+        for_each_possible_cpu(__cpu) {                                  \
+                __cpu_lockdep_stats = &per_cpu(lockdep_stats, __cpu);   \
+                __total += __cpu_lockdep_stats->ptr;                    \
+        }                                                               \
+        __total;                                                        \
+})
+#else
+# define __debug_atomic_inc(ptr)        do { } while (0)
+# define debug_atomic_inc(ptr)          do { } while (0)
+# define debug_atomic_dec(ptr)          do { } while (0)
+# define debug_atomic_read(ptr)         0
+#endif
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
new file mode 100644
index 000000000000..ef43ac4bafb5
--- /dev/null
+++ b/kernel/locking/lockdep_proc.c
@@ -0,0 +1,683 @@
+/*
+ * kernel/lockdep_proc.c
+ *
+ * Runtime locking correctness validator
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ * Code for /proc/lockdep and /proc/lockdep_stats:
+ *
+ */
+#include <linux/export.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/kallsyms.h>
+#include <linux/debug_locks.h>
+#include <linux/vmalloc.h>
+#include <linux/sort.h>
+#include <asm/uaccess.h>
+#include <asm/div64.h>
+
+#include "lockdep_internals.h"
+
+static void *l_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        return seq_list_next(v, &all_lock_classes, pos);
+}
+
+static void *l_start(struct seq_file *m, loff_t *pos)
+{
+        return seq_list_start_head(&all_lock_classes, *pos);
+}
+
+static void l_stop(struct seq_file *m, void *v)
+{
+}
+
+static void print_name(struct seq_file *m, struct lock_class *class)
+{
+        char str[KSYM_NAME_LEN];
+        const char *name = class->name;
+
+        if (!name) {
+                name = __get_key_name(class->key, str);
+                seq_printf(m, "%s", name);
+        } else{
+                seq_printf(m, "%s", name);
+                if (class->name_version > 1)
+                        seq_printf(m, "#%d", class->name_version);
+                if (class->subclass)
+                        seq_printf(m, "/%d", class->subclass);
+        }
+}
+
+static int l_show(struct seq_file *m, void *v)
+{
+        struct lock_class *class = list_entry(v, struct lock_class, lock_entry);
+        struct lock_list *entry;
+        char usage[LOCK_USAGE_CHARS];
+
+        if (v == &all_lock_classes) {
+                seq_printf(m, "all lock classes:\n");
+                return 0;
+        }
+
+        seq_printf(m, "%p", class->key);
+#ifdef CONFIG_DEBUG_LOCKDEP
+        seq_printf(m, " OPS:%8ld", class->ops);
+#endif
+#ifdef CONFIG_PROVE_LOCKING
+        seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
+        seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
+#endif
+
+        get_usage_chars(class, usage);
+        seq_printf(m, " %s", usage);
+
+        seq_printf(m, ": ");
+        print_name(m, class);
+        seq_puts(m, "\n");
+
+        list_for_each_entry(entry, &class->locks_after, entry) {
+                if (entry->distance == 1) {
+                        seq_printf(m, " -> [%p] ", entry->class->key);
+                        print_name(m, entry->class);
+                        seq_puts(m, "\n");
+                }
+        }
+        seq_puts(m, "\n");
+
+        return 0;
+}
+
+static const struct seq_operations lockdep_ops = {
+        .start  = l_start,
+        .next   = l_next,
+        .stop   = l_stop,
+        .show   = l_show,
+};
+
+static int lockdep_open(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &lockdep_ops);
+}
+
+static const struct file_operations proc_lockdep_operations = {
+        .open           = lockdep_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = seq_release,
+};
+
+#ifdef CONFIG_PROVE_LOCKING
+static void *lc_start(struct seq_file *m, loff_t *pos)
+{
+        if (*pos == 0)
+                return SEQ_START_TOKEN;
+
+        if (*pos - 1 < nr_lock_chains)
+                return lock_chains + (*pos - 1);
+
+        return NULL;
+}
+
+static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        (*pos)++;
+        return lc_start(m, pos);
+}
+
+static void lc_stop(struct seq_file *m, void *v)
+{
+}
+
+static int lc_show(struct seq_file *m, void *v)
+{
+        struct lock_chain *chain = v;
+        struct lock_class *class;
+        int i;
+
+        if (v == SEQ_START_TOKEN) {
+                seq_printf(m, "all lock chains:\n");
+                return 0;
+        }
+
+        seq_printf(m, "irq_context: %d\n", chain->irq_context);
+
+        for (i = 0; i < chain->depth; i++) {
+                class = lock_chain_get_class(chain, i);
+                if (!class->key)
+                        continue;
+
+                seq_printf(m, "[%p] ", class->key);
+                print_name(m, class);
+                seq_puts(m, "\n");
+        }
+        seq_puts(m, "\n");
+
+        return 0;
+}
+
+static const struct seq_operations lockdep_chains_ops = {
+        .start  = lc_start,
+        .next   = lc_next,
+        .stop   = lc_stop,
+        .show   = lc_show,
+};
+
+static int lockdep_chains_open(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &lockdep_chains_ops);
+}
+
+static const struct file_operations proc_lockdep_chains_operations = {
+        .open           = lockdep_chains_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = seq_release,
+};
+#endif /* CONFIG_PROVE_LOCKING */
+
+static void lockdep_stats_debug_show(struct seq_file *m)
+{
+#ifdef CONFIG_DEBUG_LOCKDEP
+        unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
+                           hi2 = debug_atomic_read(hardirqs_off_events),
+                           hr1 = debug_atomic_read(redundant_hardirqs_on),
+                           hr2 = debug_atomic_read(redundant_hardirqs_off),
+                           si1 = debug_atomic_read(softirqs_on_events),
+                           si2 = debug_atomic_read(softirqs_off_events),
+                           sr1 = debug_atomic_read(redundant_softirqs_on),
+                           sr2 = debug_atomic_read(redundant_softirqs_off);
+
+        seq_printf(m, " chain lookup misses:           %11llu\n",
+                debug_atomic_read(chain_lookup_misses));
+        seq_printf(m, " chain lookup hits:             %11llu\n",
+                debug_atomic_read(chain_lookup_hits));
+        seq_printf(m, " cyclic checks:                 %11llu\n",
+                debug_atomic_read(nr_cyclic_checks));
+        seq_printf(m, " find-mask forwards checks:     %11llu\n",
+                debug_atomic_read(nr_find_usage_forwards_checks));
+        seq_printf(m, " find-mask backwards checks:    %11llu\n",
+                debug_atomic_read(nr_find_usage_backwards_checks));
+
+        seq_printf(m, " hardirq on events:             %11llu\n", hi1);
+        seq_printf(m, " hardirq off events:            %11llu\n", hi2);
+        seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
+        seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
+        seq_printf(m, " softirq on events:             %11llu\n", si1);
+        seq_printf(m, " softirq off events:            %11llu\n", si2);
+        seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
+        seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
+#endif
+}
+
+static int lockdep_stats_show(struct seq_file *m, void *v)
+{
+        struct lock_class *class;
+        unsigned long nr_unused = 0, nr_uncategorized = 0,
+                      nr_irq_safe = 0, nr_irq_unsafe = 0,
+                      nr_softirq_safe = 0, nr_softirq_unsafe = 0,
+                      nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
+                      nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
+                      nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
+                      nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
+                      sum_forward_deps = 0;
+
+        list_for_each_entry(class, &all_lock_classes, lock_entry) {
+
+                if (class->usage_mask == 0)
+                        nr_unused++;
+                if (class->usage_mask == LOCKF_USED)
+                        nr_uncategorized++;
+                if (class->usage_mask & LOCKF_USED_IN_IRQ)
+                        nr_irq_safe++;
+                if (class->usage_mask & LOCKF_ENABLED_IRQ)
+                        nr_irq_unsafe++;
+                if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
+                        nr_softirq_safe++;
+                if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
+                        nr_softirq_unsafe++;
+                if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
+                        nr_hardirq_safe++;
+                if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
+                        nr_hardirq_unsafe++;
+                if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
+                        nr_irq_read_safe++;
+                if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
+                        nr_irq_read_unsafe++;
+                if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
+                        nr_softirq_read_safe++;
+                if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
+                        nr_softirq_read_unsafe++;
+                if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
+                        nr_hardirq_read_safe++;
+                if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
+                        nr_hardirq_read_unsafe++;
+
+#ifdef CONFIG_PROVE_LOCKING
+                sum_forward_deps += lockdep_count_forward_deps(class);
+#endif
+        }
+#ifdef CONFIG_DEBUG_LOCKDEP
+        DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
+#endif
+        seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
+                        nr_lock_classes, MAX_LOCKDEP_KEYS);
+        seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
+                        nr_list_entries, MAX_LOCKDEP_ENTRIES);
+        seq_printf(m, " indirect dependencies:         %11lu\n",
+                        sum_forward_deps);
+
+        /*
+         * Total number of dependencies:
+         *
+         * All irq-safe locks may nest inside irq-unsafe locks,
+         * plus all the other known dependencies:
+         */
+        seq_printf(m, " all direct dependencies:       %11lu\n",
+                        nr_irq_unsafe * nr_irq_safe +
+                        nr_hardirq_unsafe * nr_hardirq_safe +
+                        nr_list_entries);
+
+#ifdef CONFIG_PROVE_LOCKING
+        seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
+                        nr_lock_chains, MAX_LOCKDEP_CHAINS);
+        seq_printf(m, " dependency chain hlocks:       %11d [max: %lu]\n",
+                        nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
+#endif
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+        seq_printf(m, " in-hardirq chains:             %11u\n",
+                        nr_hardirq_chains);
+        seq_printf(m, " in-softirq chains:             %11u\n",
+                        nr_softirq_chains);
+#endif
+        seq_printf(m, " in-process chains:             %11u\n",
+                        nr_process_chains);
+        seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
+                        nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
+        seq_printf(m, " combined max dependencies:     %11u\n",
+                        (nr_hardirq_chains + 1) *
+                        (nr_softirq_chains + 1) *
+                        (nr_process_chains + 1)
+        );
+        seq_printf(m, " hardirq-safe locks:            %11lu\n",
+                        nr_hardirq_safe);
+        seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
+                        nr_hardirq_unsafe);
+        seq_printf(m, " softirq-safe locks:            %11lu\n",
+                        nr_softirq_safe);
+        seq_printf(m, " softirq-unsafe locks:          %11lu\n",
+                        nr_softirq_unsafe);
+        seq_printf(m, " irq-safe locks:                %11lu\n",
+                        nr_irq_safe);
+        seq_printf(m, " irq-unsafe locks:              %11lu\n",
+                        nr_irq_unsafe);
+
+        seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
+                        nr_hardirq_read_safe);
+        seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
+                        nr_hardirq_read_unsafe);
+        seq_printf(m, " softirq-read-safe locks:       %11lu\n",
+                        nr_softirq_read_safe);
+        seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
+                        nr_softirq_read_unsafe);
+        seq_printf(m, " irq-read-safe locks:           %11lu\n",
+                        nr_irq_read_safe);
+        seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
+                        nr_irq_read_unsafe);
+
+        seq_printf(m, " uncategorized locks:           %11lu\n",
+                        nr_uncategorized);
+        seq_printf(m, " unused locks:                  %11lu\n",
+                        nr_unused);
+        seq_printf(m, " max locking depth:             %11u\n",
+                        max_lockdep_depth);
+#ifdef CONFIG_PROVE_LOCKING
+        seq_printf(m, " max bfs queue depth:           %11u\n",
+                        max_bfs_queue_depth);
+#endif
+        lockdep_stats_debug_show(m);
+        seq_printf(m, " debug_locks:                   %11u\n",
+                        debug_locks);
+
+        return 0;
+}
+
+static int lockdep_stats_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, lockdep_stats_show, NULL);
+}
+
+static const struct file_operations proc_lockdep_stats_operations = {
+        .open           = lockdep_stats_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+#ifdef CONFIG_LOCK_STAT
+
+struct lock_stat_data {
+        struct lock_class *class;
+        struct lock_class_stats stats;
+};
+
+struct lock_stat_seq {
+        struct lock_stat_data *iter_end;
+        struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
+};
+
+/*
+ * sort on absolute number of contentions
+ */
+static int lock_stat_cmp(const void *l, const void *r)
+{
+        const struct lock_stat_data *dl = l, *dr = r;
+        unsigned long nl, nr;
+
+        nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
+        nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
+
+        return nr - nl;
+}
+
+static void seq_line(struct seq_file *m, char c, int offset, int length)
+{
+        int i;
+
+        for (i = 0; i < offset; i++)
+                seq_puts(m, " ");
+        for (i = 0; i < length; i++)
+                seq_printf(m, "%c", c);
+        seq_puts(m, "\n");
+}
+
+static void snprint_time(char *buf, size_t bufsiz, s64 nr)
+{
+        s64 div;
+        s32 rem;
+
+        nr += 5; /* for display rounding */
+        div = div_s64_rem(nr, 1000, &rem);
+        snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
+}
+
+static void seq_time(struct seq_file *m, s64 time)
+{
+        char num[15];
+
+        snprint_time(num, sizeof(num), time);
+        seq_printf(m, " %14s", num);
+}
+
+static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
+{
+        seq_printf(m, "%14lu", lt->nr);
+        seq_time(m, lt->min);
+        seq_time(m, lt->max);
+        seq_time(m, lt->total);
+        seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
+}
+
+static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
+{
+        char name[39];
+        struct lock_class *class;
+        struct lock_class_stats *stats;
+        int i, namelen;
+
+        class = data->class;
+        stats = &data->stats;
+
+        namelen = 38;
+        if (class->name_version > 1)
+                namelen -= 2; /* XXX truncates versions > 9 */
+        if (class->subclass)
+                namelen -= 2;
+
+        if (!class->name) {
+                char str[KSYM_NAME_LEN];
+                const char *key_name;
+
+                key_name = __get_key_name(class->key, str);
+                snprintf(name, namelen, "%s", key_name);
+        } else {
+                snprintf(name, namelen, "%s", class->name);
+        }
+        namelen = strlen(name);
+        if (class->name_version > 1) {
+                snprintf(name+namelen, 3, "#%d", class->name_version);
+                namelen += 2;
+        }
+        if (class->subclass) {
+                snprintf(name+namelen, 3, "/%d", class->subclass);
+                namelen += 2;
+        }
+
+        if (stats->write_holdtime.nr) {
+                if (stats->read_holdtime.nr)
+                        seq_printf(m, "%38s-W:", name);
+                else
+                        seq_printf(m, "%40s:", name);
+
+                seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
+                seq_lock_time(m, &stats->write_waittime);
+                seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
+                seq_lock_time(m, &stats->write_holdtime);
+                seq_puts(m, "\n");
+        }
+
+        if (stats->read_holdtime.nr) {
+                seq_printf(m, "%38s-R:", name);
+                seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
+                seq_lock_time(m, &stats->read_waittime);
+                seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
+                seq_lock_time(m, &stats->read_holdtime);
+                seq_puts(m, "\n");
+        }
+
+        if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
+                return;
+
+        if (stats->read_holdtime.nr)
+                namelen += 2;
+
+        for (i = 0; i < LOCKSTAT_POINTS; i++) {
+                char ip[32];
+
+                if (class->contention_point[i] == 0)
+                        break;
+
+                if (!i)
+                        seq_line(m, '-', 40-namelen, namelen);
+
+                snprintf(ip, sizeof(ip), "[<%p>]",
+                                (void *)class->contention_point[i]);
+                seq_printf(m, "%40s %14lu %29s %pS\n",
+                           name, stats->contention_point[i],
+                           ip, (void *)class->contention_point[i]);
+        }
+        for (i = 0; i < LOCKSTAT_POINTS; i++) {
+                char ip[32];
+
+                if (class->contending_point[i] == 0)
+                        break;
+
+                if (!i)
+                        seq_line(m, '-', 40-namelen, namelen);
+
+                snprintf(ip, sizeof(ip), "[<%p>]",
+                                (void *)class->contending_point[i]);
+                seq_printf(m, "%40s %14lu %29s %pS\n",
+                           name, stats->contending_point[i],
+                           ip, (void *)class->contending_point[i]);
+        }
+        if (i) {
+                seq_puts(m, "\n");
+                seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
+                seq_puts(m, "\n");
+        }
+}
+
+static void seq_header(struct seq_file *m)
+{
+        seq_puts(m, "lock_stat version 0.4\n");
+
+        if (unlikely(!debug_locks))
+                seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
+
+        seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
+        seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
+                        "%14s %14s\n",
+                        "class name",
+                        "con-bounces",
+                        "contentions",
+                        "waittime-min",
+                        "waittime-max",
+                        "waittime-total",
+                        "waittime-avg",
+                        "acq-bounces",
+                        "acquisitions",
+                        "holdtime-min",
+                        "holdtime-max",
+                        "holdtime-total",
+                        "holdtime-avg");
+        seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
+        seq_printf(m, "\n");
+}
+
+static void *ls_start(struct seq_file *m, loff_t *pos)
+{
+        struct lock_stat_seq *data = m->private;
+        struct lock_stat_data *iter;
+
+        if (*pos == 0)
+                return SEQ_START_TOKEN;
+
+        iter = data->stats + (*pos - 1);
+        if (iter >= data->iter_end)
+                iter = NULL;
+
+        return iter;
+}
+
+static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        (*pos)++;
+        return ls_start(m, pos);
+}
+
+static void ls_stop(struct seq_file *m, void *v)
+{
+}
+
+static int ls_show(struct seq_file *m, void *v)
+{
+        if (v == SEQ_START_TOKEN)
+                seq_header(m);
+        else
+                seq_stats(m, v);
+
+        return 0;
+}
+
+static const struct seq_operations lockstat_ops = {
+        .start  = ls_start,
+        .next   = ls_next,
+        .stop   = ls_stop,
+        .show   = ls_show,
+};
+
+static int lock_stat_open(struct inode *inode, struct file *file)
+{
+        int res;
+        struct lock_class *class;
+        struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
+
+        if (!data)
+                return -ENOMEM;
+
+        res = seq_open(file, &lockstat_ops);
+        if (!res) {
+                struct lock_stat_data *iter = data->stats;
+                struct seq_file *m = file->private_data;
+
+                list_for_each_entry(class, &all_lock_classes, lock_entry) {
+                        iter->class = class;
+                        iter->stats = lock_stats(class);
+                        iter++;
+                }
+                data->iter_end = iter;
+
+                sort(data->stats, data->iter_end - data->stats,
+                                sizeof(struct lock_stat_data),
+                                lock_stat_cmp, NULL);
+
+                m->private = data;
+        } else
+                vfree(data);
+
+        return res;
+}
+
+static ssize_t lock_stat_write(struct file *file, const char __user *buf,
+                               size_t count, loff_t *ppos)
+{
+        struct lock_class *class;
+        char c;
+
+        if (count) {
+                if (get_user(c, buf))
+                        return -EFAULT;
+
+                if (c != '0')
+                        return count;
+
+                list_for_each_entry(class, &all_lock_classes, lock_entry)
+                        clear_lock_stats(class);
+        }
+        return count;
+}
+
+static int lock_stat_release(struct inode *inode, struct file *file)
+{
+        struct seq_file *seq = file->private_data;
+
+        vfree(seq->private);
+        return seq_release(inode, file);
+}
+
+static const struct file_operations proc_lock_stat_operations = {
+        .open           = lock_stat_open,
+        .write          = lock_stat_write,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = lock_stat_release,
+};
+#endif /* CONFIG_LOCK_STAT */
+
+static int __init lockdep_proc_init(void)
+{
+        proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
+#ifdef CONFIG_PROVE_LOCKING
+        proc_create("lockdep_chains", S_IRUSR, NULL,
+                    &proc_lockdep_chains_operations);
+#endif
+        proc_create("lockdep_stats", S_IRUSR, NULL,
+                    &proc_lockdep_stats_operations);
+
+#ifdef CONFIG_LOCK_STAT
+        proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL,
+                    &proc_lock_stat_operations);
+#endif
+
+        return 0;
+}
+
+__initcall(lockdep_proc_init);
+
diff --git a/kernel/locking/lockdep_states.h b/kernel/locking/lockdep_states.h
new file mode 100644
index 000000000000..995b0cc2b84c
--- /dev/null
+++ b/kernel/locking/lockdep_states.h
@@ -0,0 +1,9 @@
+/*
+ * Lockdep states,
+ *
+ * please update XXX_LOCK_USAGE_STATES in include/linux/lockdep.h whenever
+ * you add one, or come up with a nice dynamic solution.
+ */
+LOCKDEP_STATE(HARDIRQ)
+LOCKDEP_STATE(SOFTIRQ)
+LOCKDEP_STATE(RECLAIM_FS)
diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c
new file mode 100644
index 000000000000..7e3443fe1f48
--- /dev/null
+++ b/kernel/locking/mutex-debug.c
@@ -0,0 +1,110 @@
+/*
+ * kernel/mutex-debug.c
+ *
+ * Debugging code for mutexes
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * lock debugging, locking tree, deadlock detection started by:
+ *
+ *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
+ *  Released under the General Public License (GPL).
+ */
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/poison.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+
+#include "mutex-debug.h"
+
+/*
+ * Must be called with lock->wait_lock held.
+ */
+void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
+{
+        memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
+        waiter->magic = waiter;
+        INIT_LIST_HEAD(&waiter->list);
+}
+
+void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
+{
+        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
+        DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
+        DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
+        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
+}
+
+void debug_mutex_free_waiter(struct mutex_waiter *waiter)
+{
+        DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
+        memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
+}
+
+void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+                            struct thread_info *ti)
+{
+        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
+
+        /* Mark the current thread as blocked on the lock: */
+        ti->task->blocked_on = waiter;
+}
+
+void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+                         struct thread_info *ti)
+{
+        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
+        DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
+        DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
+        ti->task->blocked_on = NULL;
+
+        list_del_init(&waiter->list);
+        waiter->task = NULL;
+}
+
+void debug_mutex_unlock(struct mutex *lock)
+{
+        if (unlikely(!debug_locks))
+                return;
+
+        DEBUG_LOCKS_WARN_ON(lock->magic != lock);
+        DEBUG_LOCKS_WARN_ON(lock->owner != current);
+        DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
+        mutex_clear_owner(lock);
+}
+
+void debug_mutex_init(struct mutex *lock, const char *name,
+                      struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /*
+         * Make sure we are not reinitializing a held lock:
+         */
+        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+        lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+        lock->magic = lock;
+}
+
+/***
+ * mutex_destroy - mark a mutex unusable
+ * @lock: the mutex to be destroyed
+ *
+ * This function marks the mutex uninitialized, and any subsequent
+ * use of the mutex is forbidden. The mutex must not be locked when
+ * this function is called.
+ */
+void mutex_destroy(struct mutex *lock)
+{
+        DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
+        lock->magic = NULL;
+}
+
+EXPORT_SYMBOL_GPL(mutex_destroy);
diff --git a/kernel/locking/mutex-debug.h b/kernel/locking/mutex-debug.h
new file mode 100644
index 000000000000..0799fd3e4cfa
--- /dev/null
+++ b/kernel/locking/mutex-debug.h
@@ -0,0 +1,55 @@
+/*
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * This file contains mutex debugging related internal declarations,
+ * prototypes and inline functions, for the CONFIG_DEBUG_MUTEXES case.
+ * More details are in kernel/mutex-debug.c.
+ */
+
+/*
+ * This must be called with lock->wait_lock held.
+ */
+extern void debug_mutex_lock_common(struct mutex *lock,
+                                    struct mutex_waiter *waiter);
+extern void debug_mutex_wake_waiter(struct mutex *lock,
+                                    struct mutex_waiter *waiter);
+extern void debug_mutex_free_waiter(struct mutex_waiter *waiter);
+extern void debug_mutex_add_waiter(struct mutex *lock,
+                                   struct mutex_waiter *waiter,
+                                   struct thread_info *ti);
+extern void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+                                struct thread_info *ti);
+extern void debug_mutex_unlock(struct mutex *lock);
+extern void debug_mutex_init(struct mutex *lock, const char *name,
+                             struct lock_class_key *key);
+
+static inline void mutex_set_owner(struct mutex *lock)
+{
+        lock->owner = current;
+}
+
+static inline void mutex_clear_owner(struct mutex *lock)
+{
+        lock->owner = NULL;
+}
+
+#define spin_lock_mutex(lock, flags)                    \
+        do {                                            \
+                struct mutex *l = container_of(lock, struct mutex, wait_lock); \
+                                                        \
+                DEBUG_LOCKS_WARN_ON(in_interrupt());    \
+                local_irq_save(flags);                  \
+                arch_spin_lock(&(lock)->rlock.raw_lock);\
+                DEBUG_LOCKS_WARN_ON(l->magic != l);     \
+        } while (0)
+
+#define spin_unlock_mutex(lock, flags)                          \
+        do {                                                    \
+                arch_spin_unlock(&(lock)->rlock.raw_lock);      \
+                local_irq_restore(flags);                       \
+                preempt_check_resched();                        \
+        } while (0)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
new file mode 100644
index 000000000000..4dd6e4c219de
--- /dev/null
+++ b/kernel/locking/mutex.c
@@ -0,0 +1,960 @@
+/*
+ * kernel/locking/mutex.c
+ *
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * Started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
+ * David Howells for suggestions and improvements.
+ *
+ *  - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline
+ *    from the -rt tree, where it was originally implemented for rtmutexes
+ *    by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale
+ *    and Sven Dietrich.
+ *
+ * Also see Documentation/mutex-design.txt.
+ */
+#include <linux/mutex.h>
+#include <linux/ww_mutex.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+
+/*
+ * In the DEBUG case we are using the "NULL fastpath" for mutexes,
+ * which forces all calls into the slowpath:
+ */
+#ifdef CONFIG_DEBUG_MUTEXES
+# include "mutex-debug.h"
+# include <asm-generic/mutex-null.h>
+#else
+# include "mutex.h"
+# include <asm/mutex.h>
+#endif
+
+/*
+ * A negative mutex count indicates that waiters are sleeping waiting for the
+ * mutex.
+ */
+#define MUTEX_SHOW_NO_WAITER(mutex)     (atomic_read(&(mutex)->count) >= 0)
+
+void
+__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
+{
+        atomic_set(&lock->count, 1);
+        spin_lock_init(&lock->wait_lock);
+        INIT_LIST_HEAD(&lock->wait_list);
+        mutex_clear_owner(lock);
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+        lock->spin_mlock = NULL;
+#endif
+
+        debug_mutex_init(lock, name, key);
+}
+
+EXPORT_SYMBOL(__mutex_init);
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+/*
+ * We split the mutex lock/unlock logic into separate fastpath and
+ * slowpath functions, to reduce the register pressure on the fastpath.
+ * We also put the fastpath first in the kernel image, to make sure the
+ * branch is predicted by the CPU as default-untaken.
+ */
+static __used noinline void __sched
+__mutex_lock_slowpath(atomic_t *lock_count);
+
+/**
+ * mutex_lock - acquire the mutex
+ * @lock: the mutex to be acquired
+ *
+ * Lock the mutex exclusively for this task. If the mutex is not
+ * available right now, it will sleep until it can get it.
+ *
+ * The mutex must later on be released by the same task that
+ * acquired it. Recursive locking is not allowed. The task
+ * may not exit without first unlocking the mutex. Also, kernel
+ * memory where the mutex resides mutex must not be freed with
+ * the mutex still locked. The mutex must first be initialized
+ * (or statically defined) before it can be locked. memset()-ing
+ * the mutex to 0 is not allowed.
+ *
+ * ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging
+ *   checks that will enforce the restrictions and will also do
+ *   deadlock debugging. )
+ *
+ * This function is similar to (but not equivalent to) down().
+ */
+void __sched mutex_lock(struct mutex *lock)
+{
+        might_sleep();
+        /*
+         * The locking fastpath is the 1->0 transition from
+         * 'unlocked' into 'locked' state.
+         */
+        __mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath);
+        mutex_set_owner(lock);
+}
+
+EXPORT_SYMBOL(mutex_lock);
+#endif
+
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+/*
+ * In order to avoid a stampede of mutex spinners from acquiring the mutex
+ * more or less simultaneously, the spinners need to acquire a MCS lock
+ * first before spinning on the owner field.
+ *
+ * We don't inline mspin_lock() so that perf can correctly account for the
+ * time spent in this lock function.
+ */
+struct mspin_node {
+        struct mspin_node *next ;
+        int               locked;       /* 1 if lock acquired */
+};
+#define MLOCK(mutex)    ((struct mspin_node **)&((mutex)->spin_mlock))
+
+static noinline
+void mspin_lock(struct mspin_node **lock, struct mspin_node *node)
+{
+        struct mspin_node *prev;
+
+        /* Init node */
+        node->locked = 0;
+        node->next   = NULL;
+
+        prev = xchg(lock, node);
+        if (likely(prev == NULL)) {
+                /* Lock acquired */
+                node->locked = 1;
+                return;
+        }
+        ACCESS_ONCE(prev->next) = node;
+        smp_wmb();
+        /* Wait until the lock holder passes the lock down */
+        while (!ACCESS_ONCE(node->locked))
+                arch_mutex_cpu_relax();
+}
+
+static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node)
+{
+        struct mspin_node *next = ACCESS_ONCE(node->next);
+
+        if (likely(!next)) {
+                /*
+                 * Release the lock by setting it to NULL
+                 */
+                if (cmpxchg(lock, node, NULL) == node)
+                        return;
+                /* Wait until the next pointer is set */
+                while (!(next = ACCESS_ONCE(node->next)))
+                        arch_mutex_cpu_relax();
+        }
+        ACCESS_ONCE(next->locked) = 1;
+        smp_wmb();
+}
+
+/*
+ * Mutex spinning code migrated from kernel/sched/core.c
+ */
+
+static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
+{
+        if (lock->owner != owner)
+                return false;
+
+        /*
+         * Ensure we emit the owner->on_cpu, dereference _after_ checking
+         * lock->owner still matches owner, if that fails, owner might
+         * point to free()d memory, if it still matches, the rcu_read_lock()
+         * ensures the memory stays valid.
+         */
+        barrier();
+
+        return owner->on_cpu;
+}
+
+/*
+ * Look out! "owner" is an entirely speculative pointer
+ * access and not reliable.
+ */
+static noinline
+int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
+{
+        rcu_read_lock();
+        while (owner_running(lock, owner)) {
+                if (need_resched())
+                        break;
+
+                arch_mutex_cpu_relax();
+        }
+        rcu_read_unlock();
+
+        /*
+         * We break out the loop above on need_resched() and when the
+         * owner changed, which is a sign for heavy contention. Return
+         * success only when lock->owner is NULL.
+         */
+        return lock->owner == NULL;
+}
+
+/*
+ * Initial check for entering the mutex spinning loop
+ */
+static inline int mutex_can_spin_on_owner(struct mutex *lock)
+{
+        struct task_struct *owner;
+        int retval = 1;
+
+        rcu_read_lock();
+        owner = ACCESS_ONCE(lock->owner);
+        if (owner)
+                retval = owner->on_cpu;
+        rcu_read_unlock();
+        /*
+         * if lock->owner is not set, the mutex owner may have just acquired
+         * it and not set the owner yet or the mutex has been released.
+         */
+        return retval;
+}
+#endif
+
+static __used noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count);
+
+/**
+ * mutex_unlock - release the mutex
+ * @lock: the mutex to be released
+ *
+ * Unlock a mutex that has been locked by this task previously.
+ *
+ * This function must not be used in interrupt context. Unlocking
+ * of a not locked mutex is not allowed.
+ *
+ * This function is similar to (but not equivalent to) up().
+ */
+void __sched mutex_unlock(struct mutex *lock)
+{
+        /*
+         * The unlocking fastpath is the 0->1 transition from 'locked'
+         * into 'unlocked' state:
+         */
+#ifndef CONFIG_DEBUG_MUTEXES
+        /*
+         * When debugging is enabled we must not clear the owner before time,
+         * the slow path will always be taken, and that clears the owner field
+         * after verifying that it was indeed current.
+         */
+        mutex_clear_owner(lock);
+#endif
+        __mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);
+}
+
+EXPORT_SYMBOL(mutex_unlock);
+
+/**
+ * ww_mutex_unlock - release the w/w mutex
+ * @lock: the mutex to be released
+ *
+ * Unlock a mutex that has been locked by this task previously with any of the
+ * ww_mutex_lock* functions (with or without an acquire context). It is
+ * forbidden to release the locks after releasing the acquire context.
+ *
+ * This function must not be used in interrupt context. Unlocking
+ * of a unlocked mutex is not allowed.
+ */
+void __sched ww_mutex_unlock(struct ww_mutex *lock)
+{
+        /*
+         * The unlocking fastpath is the 0->1 transition from 'locked'
+         * into 'unlocked' state:
+         */
+        if (lock->ctx) {
+#ifdef CONFIG_DEBUG_MUTEXES
+                DEBUG_LOCKS_WARN_ON(!lock->ctx->acquired);
+#endif
+                if (lock->ctx->acquired > 0)
+                        lock->ctx->acquired--;
+                lock->ctx = NULL;
+        }
+
+#ifndef CONFIG_DEBUG_MUTEXES
+        /*
+         * When debugging is enabled we must not clear the owner before time,
+         * the slow path will always be taken, and that clears the owner field
+         * after verifying that it was indeed current.
+         */
+        mutex_clear_owner(&lock->base);
+#endif
+        __mutex_fastpath_unlock(&lock->base.count, __mutex_unlock_slowpath);
+}
+EXPORT_SYMBOL(ww_mutex_unlock);
+
+static inline int __sched
+__mutex_lock_check_stamp(struct mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+        struct ww_acquire_ctx *hold_ctx = ACCESS_ONCE(ww->ctx);
+
+        if (!hold_ctx)
+                return 0;
+
+        if (unlikely(ctx == hold_ctx))
+                return -EALREADY;
+
+        if (ctx->stamp - hold_ctx->stamp <= LONG_MAX &&
+            (ctx->stamp != hold_ctx->stamp || ctx > hold_ctx)) {
+#ifdef CONFIG_DEBUG_MUTEXES
+                DEBUG_LOCKS_WARN_ON(ctx->contending_lock);
+                ctx->contending_lock = ww;
+#endif
+                return -EDEADLK;
+        }
+
+        return 0;
+}
+
+static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
+                                                   struct ww_acquire_ctx *ww_ctx)
+{
+#ifdef CONFIG_DEBUG_MUTEXES
+        /*
+         * If this WARN_ON triggers, you used ww_mutex_lock to acquire,
+         * but released with a normal mutex_unlock in this call.
+         *
+         * This should never happen, always use ww_mutex_unlock.
+         */
+        DEBUG_LOCKS_WARN_ON(ww->ctx);
+
+        /*
+         * Not quite done after calling ww_acquire_done() ?
+         */
+        DEBUG_LOCKS_WARN_ON(ww_ctx->done_acquire);
+
+        if (ww_ctx->contending_lock) {
+                /*
+                 * After -EDEADLK you tried to
+                 * acquire a different ww_mutex? Bad!
+                 */
+                DEBUG_LOCKS_WARN_ON(ww_ctx->contending_lock != ww);
+
+                /*
+                 * You called ww_mutex_lock after receiving -EDEADLK,
+                 * but 'forgot' to unlock everything else first?
+                 */
+                DEBUG_LOCKS_WARN_ON(ww_ctx->acquired > 0);
+                ww_ctx->contending_lock = NULL;
+        }
+
+        /*
+         * Naughty, using a different class will lead to undefined behavior!
+         */
+        DEBUG_LOCKS_WARN_ON(ww_ctx->ww_class != ww->ww_class);
+#endif
+        ww_ctx->acquired++;
+}
+
+/*
+ * after acquiring lock with fastpath or when we lost out in contested
+ * slowpath, set ctx and wake up any waiters so they can recheck.
+ *
+ * This function is never called when CONFIG_DEBUG_LOCK_ALLOC is set,
+ * as the fastpath and opportunistic spinning are disabled in that case.
+ */
+static __always_inline void
+ww_mutex_set_context_fastpath(struct ww_mutex *lock,
+                               struct ww_acquire_ctx *ctx)
+{
+        unsigned long flags;
+        struct mutex_waiter *cur;
+
+        ww_mutex_lock_acquired(lock, ctx);
+
+        lock->ctx = ctx;
+
+        /*
+         * The lock->ctx update should be visible on all cores before
+         * the atomic read is done, otherwise contended waiters might be
+         * missed. The contended waiters will either see ww_ctx == NULL
+         * and keep spinning, or it will acquire wait_lock, add itself
+         * to waiter list and sleep.
+         */
+        smp_mb(); /* ^^^ */
+
+        /*
+         * Check if lock is contended, if not there is nobody to wake up
+         */
+        if (likely(atomic_read(&lock->base.count) == 0))
+                return;
+
+        /*
+         * Uh oh, we raced in fastpath, wake up everyone in this case,
+         * so they can see the new lock->ctx.
+         */
+        spin_lock_mutex(&lock->base.wait_lock, flags);
+        list_for_each_entry(cur, &lock->base.wait_list, list) {
+                debug_mutex_wake_waiter(&lock->base, cur);
+                wake_up_process(cur->task);
+        }
+        spin_unlock_mutex(&lock->base.wait_lock, flags);
+}
+
+/*
+ * Lock a mutex (possibly interruptible), slowpath:
+ */
+static __always_inline int __sched
+__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
+                    struct lockdep_map *nest_lock, unsigned long ip,
+                    struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
+{
+        struct task_struct *task = current;
+        struct mutex_waiter waiter;
+        unsigned long flags;
+        int ret;
+
+        preempt_disable();
+        mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
+
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+        /*
+         * Optimistic spinning.
+         *
+         * We try to spin for acquisition when we find that there are no
+         * pending waiters and the lock owner is currently running on a
+         * (different) CPU.
+         *
+         * The rationale is that if the lock owner is running, it is likely to
+         * release the lock soon.
+         *
+         * Since this needs the lock owner, and this mutex implementation
+         * doesn't track the owner atomically in the lock field, we need to
+         * track it non-atomically.
+         *
+         * We can't do this for DEBUG_MUTEXES because that relies on wait_lock
+         * to serialize everything.
+         *
+         * The mutex spinners are queued up using MCS lock so that only one
+         * spinner can compete for the mutex. However, if mutex spinning isn't
+         * going to happen, there is no point in going through the lock/unlock
+         * overhead.
+         */
+        if (!mutex_can_spin_on_owner(lock))
+                goto slowpath;
+
+        for (;;) {
+                struct task_struct *owner;
+                struct mspin_node  node;
+
+                if (use_ww_ctx && ww_ctx->acquired > 0) {
+                        struct ww_mutex *ww;
+
+                        ww = container_of(lock, struct ww_mutex, base);
+                        /*
+                         * If ww->ctx is set the contents are undefined, only
+                         * by acquiring wait_lock there is a guarantee that
+                         * they are not invalid when reading.
+                         *
+                         * As such, when deadlock detection needs to be
+                         * performed the optimistic spinning cannot be done.
+                         */
+                        if (ACCESS_ONCE(ww->ctx))
+                                goto slowpath;
+                }
+
+                /*
+                 * If there's an owner, wait for it to either
+                 * release the lock or go to sleep.
+                 */
+                mspin_lock(MLOCK(lock), &node);
+                owner = ACCESS_ONCE(lock->owner);
+                if (owner && !mutex_spin_on_owner(lock, owner)) {
+                        mspin_unlock(MLOCK(lock), &node);
+                        goto slowpath;
+                }
+
+                if ((atomic_read(&lock->count) == 1) &&
+                    (atomic_cmpxchg(&lock->count, 1, 0) == 1)) {
+                        lock_acquired(&lock->dep_map, ip);
+                        if (use_ww_ctx) {
+                                struct ww_mutex *ww;
+                                ww = container_of(lock, struct ww_mutex, base);
+
+                                ww_mutex_set_context_fastpath(ww, ww_ctx);
+                        }
+
+                        mutex_set_owner(lock);
+                        mspin_unlock(MLOCK(lock), &node);
+                        preempt_enable();
+                        return 0;
+                }
+                mspin_unlock(MLOCK(lock), &node);
+
+                /*
+                 * When there's no owner, we might have preempted between the
+                 * owner acquiring the lock and setting the owner field. If
+                 * we're an RT task that will live-lock because we won't let
+                 * the owner complete.
+                 */
+                if (!owner && (need_resched() || rt_task(task)))
+                        goto slowpath;
+
+                /*
+                 * The cpu_relax() call is a compiler barrier which forces
+                 * everything in this loop to be re-loaded. We don't need
+                 * memory barriers as we'll eventually observe the right
+                 * values at the cost of a few extra spins.
+                 */
+                arch_mutex_cpu_relax();
+        }
+slowpath:
+#endif
+        spin_lock_mutex(&lock->wait_lock, flags);
+
+        /* once more, can we acquire the lock? */
+        if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, 0) == 1))
+                goto skip_wait;
+
+        debug_mutex_lock_common(lock, &waiter);
+        debug_mutex_add_waiter(lock, &waiter, task_thread_info(task));
+
+        /* add waiting tasks to the end of the waitqueue (FIFO): */
+        list_add_tail(&waiter.list, &lock->wait_list);
+        waiter.task = task;
+
+        lock_contended(&lock->dep_map, ip);
+
+        for (;;) {
+                /*
+                 * Lets try to take the lock again - this is needed even if
+                 * we get here for the first time (shortly after failing to
+                 * acquire the lock), to make sure that we get a wakeup once
+                 * it's unlocked. Later on, if we sleep, this is the
+                 * operation that gives us the lock. We xchg it to -1, so
+                 * that when we release the lock, we properly wake up the
+                 * other waiters:
+                 */
+                if (MUTEX_SHOW_NO_WAITER(lock) &&
+                    (atomic_xchg(&lock->count, -1) == 1))
+                        break;
+
+                /*
+                 * got a signal? (This code gets eliminated in the
+                 * TASK_UNINTERRUPTIBLE case.)
+                 */
+                if (unlikely(signal_pending_state(state, task))) {
+                        ret = -EINTR;
+                        goto err;
+                }
+
+                if (use_ww_ctx && ww_ctx->acquired > 0) {
+                        ret = __mutex_lock_check_stamp(lock, ww_ctx);
+                        if (ret)
+                                goto err;
+                }
+
+                __set_task_state(task, state);
+
+                /* didn't get the lock, go to sleep: */
+                spin_unlock_mutex(&lock->wait_lock, flags);
+                schedule_preempt_disabled();
+                spin_lock_mutex(&lock->wait_lock, flags);
+        }
+        mutex_remove_waiter(lock, &waiter, current_thread_info());
+        /* set it to 0 if there are no waiters left: */
+        if (likely(list_empty(&lock->wait_list)))
+                atomic_set(&lock->count, 0);
+        debug_mutex_free_waiter(&waiter);
+
+skip_wait:
+        /* got the lock - cleanup and rejoice! */
+        lock_acquired(&lock->dep_map, ip);
+        mutex_set_owner(lock);
+
+        if (use_ww_ctx) {
+                struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+                struct mutex_waiter *cur;
+
+                /*
+                 * This branch gets optimized out for the common case,
+                 * and is only important for ww_mutex_lock.
+                 */
+                ww_mutex_lock_acquired(ww, ww_ctx);
+                ww->ctx = ww_ctx;
+
+                /*
+                 * Give any possible sleeping processes the chance to wake up,
+                 * so they can recheck if they have to back off.
+                 */
+                list_for_each_entry(cur, &lock->wait_list, list) {
+                        debug_mutex_wake_waiter(lock, cur);
+                        wake_up_process(cur->task);
+                }
+        }
+
+        spin_unlock_mutex(&lock->wait_lock, flags);
+        preempt_enable();
+        return 0;
+
+err:
+        mutex_remove_waiter(lock, &waiter, task_thread_info(task));
+        spin_unlock_mutex(&lock->wait_lock, flags);
+        debug_mutex_free_waiter(&waiter);
+        mutex_release(&lock->dep_map, 1, ip);
+        preempt_enable();
+        return ret;
+}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void __sched
+mutex_lock_nested(struct mutex *lock, unsigned int subclass)
+{
+        might_sleep();
+        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+                            subclass, NULL, _RET_IP_, NULL, 0);
+}
+
+EXPORT_SYMBOL_GPL(mutex_lock_nested);
+
+void __sched
+_mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
+{
+        might_sleep();
+        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+                            0, nest, _RET_IP_, NULL, 0);
+}
+
+EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
+
+int __sched
+mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
+{
+        might_sleep();
+        return __mutex_lock_common(lock, TASK_KILLABLE,
+                                   subclass, NULL, _RET_IP_, NULL, 0);
+}
+EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
+
+int __sched
+mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass)
+{
+        might_sleep();
+        return __mutex_lock_common(lock, TASK_INTERRUPTIBLE,
+                                   subclass, NULL, _RET_IP_, NULL, 0);
+}
+
+EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
+
+static inline int
+ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+        unsigned tmp;
+
+        if (ctx->deadlock_inject_countdown-- == 0) {
+                tmp = ctx->deadlock_inject_interval;
+                if (tmp > UINT_MAX/4)
+                        tmp = UINT_MAX;
+                else
+                        tmp = tmp*2 + tmp + tmp/2;
+
+                ctx->deadlock_inject_interval = tmp;
+                ctx->deadlock_inject_countdown = tmp;
+                ctx->contending_lock = lock;
+
+                ww_mutex_unlock(lock);
+
+                return -EDEADLK;
+        }
+#endif
+
+        return 0;
+}
+
+int __sched
+__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        int ret;
+
+        might_sleep();
+        ret =  __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE,
+                                   0, &ctx->dep_map, _RET_IP_, ctx, 1);
+        if (!ret && ctx->acquired > 1)
+                return ww_mutex_deadlock_injection(lock, ctx);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(__ww_mutex_lock);
+
+int __sched
+__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        int ret;
+
+        might_sleep();
+        ret = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE,
+                                  0, &ctx->dep_map, _RET_IP_, ctx, 1);
+
+        if (!ret && ctx->acquired > 1)
+                return ww_mutex_deadlock_injection(lock, ctx);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(__ww_mutex_lock_interruptible);
+
+#endif
+
+/*
+ * Release the lock, slowpath:
+ */
+static inline void
+__mutex_unlock_common_slowpath(atomic_t *lock_count, int nested)
+{
+        struct mutex *lock = container_of(lock_count, struct mutex, count);
+        unsigned long flags;
+
+        spin_lock_mutex(&lock->wait_lock, flags);
+        mutex_release(&lock->dep_map, nested, _RET_IP_);
+        debug_mutex_unlock(lock);
+
+        /*
+         * some architectures leave the lock unlocked in the fastpath failure
+         * case, others need to leave it locked. In the later case we have to
+         * unlock it here
+         */
+        if (__mutex_slowpath_needs_to_unlock())
+                atomic_set(&lock->count, 1);
+
+        if (!list_empty(&lock->wait_list)) {
+                /* get the first entry from the wait-list: */
+                struct mutex_waiter *waiter =
+                                list_entry(lock->wait_list.next,
+                                           struct mutex_waiter, list);
+
+                debug_mutex_wake_waiter(lock, waiter);
+
+                wake_up_process(waiter->task);
+        }
+
+        spin_unlock_mutex(&lock->wait_lock, flags);
+}
+
+/*
+ * Release the lock, slowpath:
+ */
+static __used noinline void
+__mutex_unlock_slowpath(atomic_t *lock_count)
+{
+        __mutex_unlock_common_slowpath(lock_count, 1);
+}
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+/*
+ * Here come the less common (and hence less performance-critical) APIs:
+ * mutex_lock_interruptible() and mutex_trylock().
+ */
+static noinline int __sched
+__mutex_lock_killable_slowpath(struct mutex *lock);
+
+static noinline int __sched
+__mutex_lock_interruptible_slowpath(struct mutex *lock);
+
+/**
+ * mutex_lock_interruptible - acquire the mutex, interruptible
+ * @lock: the mutex to be acquired
+ *
+ * Lock the mutex like mutex_lock(), and return 0 if the mutex has
+ * been acquired or sleep until the mutex becomes available. If a
+ * signal arrives while waiting for the lock then this function
+ * returns -EINTR.
+ *
+ * This function is similar to (but not equivalent to) down_interruptible().
+ */
+int __sched mutex_lock_interruptible(struct mutex *lock)
+{
+        int ret;
+
+        might_sleep();
+        ret =  __mutex_fastpath_lock_retval(&lock->count);
+        if (likely(!ret)) {
+                mutex_set_owner(lock);
+                return 0;
+        } else
+                return __mutex_lock_interruptible_slowpath(lock);
+}
+
+EXPORT_SYMBOL(mutex_lock_interruptible);
+
+int __sched mutex_lock_killable(struct mutex *lock)
+{
+        int ret;
+
+        might_sleep();
+        ret = __mutex_fastpath_lock_retval(&lock->count);
+        if (likely(!ret)) {
+                mutex_set_owner(lock);
+                return 0;
+        } else
+                return __mutex_lock_killable_slowpath(lock);
+}
+EXPORT_SYMBOL(mutex_lock_killable);
+
+static __used noinline void __sched
+__mutex_lock_slowpath(atomic_t *lock_count)
+{
+        struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+        __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0,
+                            NULL, _RET_IP_, NULL, 0);
+}
+
+static noinline int __sched
+__mutex_lock_killable_slowpath(struct mutex *lock)
+{
+        return __mutex_lock_common(lock, TASK_KILLABLE, 0,
+                                   NULL, _RET_IP_, NULL, 0);
+}
+
+static noinline int __sched
+__mutex_lock_interruptible_slowpath(struct mutex *lock)
+{
+        return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0,
+                                   NULL, _RET_IP_, NULL, 0);
+}
+
+static noinline int __sched
+__ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        return __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, 0,
+                                   NULL, _RET_IP_, ctx, 1);
+}
+
+static noinline int __sched
+__ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
+                                            struct ww_acquire_ctx *ctx)
+{
+        return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, 0,
+                                   NULL, _RET_IP_, ctx, 1);
+}
+
+#endif
+
+/*
+ * Spinlock based trylock, we take the spinlock and check whether we
+ * can get the lock:
+ */
+static inline int __mutex_trylock_slowpath(atomic_t *lock_count)
+{
+        struct mutex *lock = container_of(lock_count, struct mutex, count);
+        unsigned long flags;
+        int prev;
+
+        spin_lock_mutex(&lock->wait_lock, flags);
+
+        prev = atomic_xchg(&lock->count, -1);
+        if (likely(prev == 1)) {
+                mutex_set_owner(lock);
+                mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+        }
+
+        /* Set it back to 0 if there are no waiters: */
+        if (likely(list_empty(&lock->wait_list)))
+                atomic_set(&lock->count, 0);
+
+        spin_unlock_mutex(&lock->wait_lock, flags);
+
+        return prev == 1;
+}
+
+/**
+ * mutex_trylock - try to acquire the mutex, without waiting
+ * @lock: the mutex to be acquired
+ *
+ * Try to acquire the mutex atomically. Returns 1 if the mutex
+ * has been acquired successfully, and 0 on contention.
+ *
+ * NOTE: this function follows the spin_trylock() convention, so
+ * it is negated from the down_trylock() return values! Be careful
+ * about this when converting semaphore users to mutexes.
+ *
+ * This function must not be used in interrupt context. The
+ * mutex must be released by the same task that acquired it.
+ */
+int __sched mutex_trylock(struct mutex *lock)
+{
+        int ret;
+
+        ret = __mutex_fastpath_trylock(&lock->count, __mutex_trylock_slowpath);
+        if (ret)
+                mutex_set_owner(lock);
+
+        return ret;
+}
+EXPORT_SYMBOL(mutex_trylock);
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+int __sched
+__ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        int ret;
+
+        might_sleep();
+
+        ret = __mutex_fastpath_lock_retval(&lock->base.count);
+
+        if (likely(!ret)) {
+                ww_mutex_set_context_fastpath(lock, ctx);
+                mutex_set_owner(&lock->base);
+        } else
+                ret = __ww_mutex_lock_slowpath(lock, ctx);
+        return ret;
+}
+EXPORT_SYMBOL(__ww_mutex_lock);
+
+int __sched
+__ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+{
+        int ret;
+
+        might_sleep();
+
+        ret = __mutex_fastpath_lock_retval(&lock->base.count);
+
+        if (likely(!ret)) {
+                ww_mutex_set_context_fastpath(lock, ctx);
+                mutex_set_owner(&lock->base);
+        } else
+                ret = __ww_mutex_lock_interruptible_slowpath(lock, ctx);
+        return ret;
+}
+EXPORT_SYMBOL(__ww_mutex_lock_interruptible);
+
+#endif
+
+/**
+ * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
+ * @cnt: the atomic which we are to dec
+ * @lock: the mutex to return holding if we dec to 0
+ *
+ * return true and hold lock if we dec to 0, return false otherwise
+ */
+int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)
+{
+        /* dec if we can't possibly hit 0 */
+        if (atomic_add_unless(cnt, -1, 1))
+                return 0;
+        /* we might hit 0, so take the lock */
+        mutex_lock(lock);
+        if (!atomic_dec_and_test(cnt)) {
+                /* when we actually did the dec, we didn't hit 0 */
+                mutex_unlock(lock);
+                return 0;
+        }
+        /* we hit 0, and we hold the lock */
+        return 1;
+}
+EXPORT_SYMBOL(atomic_dec_and_mutex_lock);
diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h
new file mode 100644
index 000000000000..4115fbf83b12
--- /dev/null
+++ b/kernel/locking/mutex.h
@@ -0,0 +1,48 @@
+/*
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * started by Ingo Molnar:
+ *
+ *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * This file contains mutex debugging related internal prototypes, for the
+ * !CONFIG_DEBUG_MUTEXES case. Most of them are NOPs:
+ */
+
+#define spin_lock_mutex(lock, flags) \
+                do { spin_lock(lock); (void)(flags); } while (0)
+#define spin_unlock_mutex(lock, flags) \
+                do { spin_unlock(lock); (void)(flags); } while (0)
+#define mutex_remove_waiter(lock, waiter, ti) \
+                __list_del((waiter)->list.prev, (waiter)->list.next)
+
+#ifdef CONFIG_SMP
+static inline void mutex_set_owner(struct mutex *lock)
+{
+        lock->owner = current;
+}
+
+static inline void mutex_clear_owner(struct mutex *lock)
+{
+        lock->owner = NULL;
+}
+#else
+static inline void mutex_set_owner(struct mutex *lock)
+{
+}
+
+static inline void mutex_clear_owner(struct mutex *lock)
+{
+}
+#endif
+
+#define debug_mutex_wake_waiter(lock, waiter)           do { } while (0)
+#define debug_mutex_free_waiter(waiter)                 do { } while (0)
+#define debug_mutex_add_waiter(lock, waiter, ti)        do { } while (0)
+#define debug_mutex_unlock(lock)                        do { } while (0)
+#define debug_mutex_init(lock, name, key)               do { } while (0)
+
+static inline void
+debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
+{
+}
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
new file mode 100644
index 000000000000..652a8ee8efe9
--- /dev/null
+++ b/kernel/locking/percpu-rwsem.c
@@ -0,0 +1,165 @@
+#include <linux/atomic.h>
+#include <linux/rwsem.h>
+#include <linux/percpu.h>
+#include <linux/wait.h>
+#include <linux/lockdep.h>
+#include <linux/percpu-rwsem.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+
+int __percpu_init_rwsem(struct percpu_rw_semaphore *brw,
+                        const char *name, struct lock_class_key *rwsem_key)
+{
+        brw->fast_read_ctr = alloc_percpu(int);
+        if (unlikely(!brw->fast_read_ctr))
+                return -ENOMEM;
+
+        /* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */
+        __init_rwsem(&brw->rw_sem, name, rwsem_key);
+        atomic_set(&brw->write_ctr, 0);
+        atomic_set(&brw->slow_read_ctr, 0);
+        init_waitqueue_head(&brw->write_waitq);
+        return 0;
+}
+
+void percpu_free_rwsem(struct percpu_rw_semaphore *brw)
+{
+        free_percpu(brw->fast_read_ctr);
+        brw->fast_read_ctr = NULL; /* catch use after free bugs */
+}
+
+/*
+ * This is the fast-path for down_read/up_read, it only needs to ensure
+ * there is no pending writer (atomic_read(write_ctr) == 0) and inc/dec the
+ * fast per-cpu counter. The writer uses synchronize_sched_expedited() to
+ * serialize with the preempt-disabled section below.
+ *
+ * The nontrivial part is that we should guarantee acquire/release semantics
+ * in case when
+ *
+ *      R_W: down_write() comes after up_read(), the writer should see all
+ *           changes done by the reader
+ * or
+ *      W_R: down_read() comes after up_write(), the reader should see all
+ *           changes done by the writer
+ *
+ * If this helper fails the callers rely on the normal rw_semaphore and
+ * atomic_dec_and_test(), so in this case we have the necessary barriers.
+ *
+ * But if it succeeds we do not have any barriers, atomic_read(write_ctr) or
+ * __this_cpu_add() below can be reordered with any LOAD/STORE done by the
+ * reader inside the critical section. See the comments in down_write and
+ * up_write below.
+ */
+static bool update_fast_ctr(struct percpu_rw_semaphore *brw, unsigned int val)
+{
+        bool success = false;
+
+        preempt_disable();
+        if (likely(!atomic_read(&brw->write_ctr))) {
+                __this_cpu_add(*brw->fast_read_ctr, val);
+                success = true;
+        }
+        preempt_enable();
+
+        return success;
+}
+
+/*
+ * Like the normal down_read() this is not recursive, the writer can
+ * come after the first percpu_down_read() and create the deadlock.
+ *
+ * Note: returns with lock_is_held(brw->rw_sem) == T for lockdep,
+ * percpu_up_read() does rwsem_release(). This pairs with the usage
+ * of ->rw_sem in percpu_down/up_write().
+ */
+void percpu_down_read(struct percpu_rw_semaphore *brw)
+{
+        might_sleep();
+        if (likely(update_fast_ctr(brw, +1))) {
+                rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_);
+                return;
+        }
+
+        down_read(&brw->rw_sem);
+        atomic_inc(&brw->slow_read_ctr);
+        /* avoid up_read()->rwsem_release() */
+        __up_read(&brw->rw_sem);
+}
+
+void percpu_up_read(struct percpu_rw_semaphore *brw)
+{
+        rwsem_release(&brw->rw_sem.dep_map, 1, _RET_IP_);
+
+        if (likely(update_fast_ctr(brw, -1)))
+                return;
+
+        /* false-positive is possible but harmless */
+        if (atomic_dec_and_test(&brw->slow_read_ctr))
+                wake_up_all(&brw->write_waitq);
+}
+
+static int clear_fast_ctr(struct percpu_rw_semaphore *brw)
+{
+        unsigned int sum = 0;
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                sum += per_cpu(*brw->fast_read_ctr, cpu);
+                per_cpu(*brw->fast_read_ctr, cpu) = 0;
+        }
+
+        return sum;
+}
+
+/*
+ * A writer increments ->write_ctr to force the readers to switch to the
+ * slow mode, note the atomic_read() check in update_fast_ctr().
+ *
+ * After that the readers can only inc/dec the slow ->slow_read_ctr counter,
+ * ->fast_read_ctr is stable. Once the writer moves its sum into the slow
+ * counter it represents the number of active readers.
+ *
+ * Finally the writer takes ->rw_sem for writing and blocks the new readers,
+ * then waits until the slow counter becomes zero.
+ */
+void percpu_down_write(struct percpu_rw_semaphore *brw)
+{
+        /* tell update_fast_ctr() there is a pending writer */
+        atomic_inc(&brw->write_ctr);
+        /*
+         * 1. Ensures that write_ctr != 0 is visible to any down_read/up_read
+         *    so that update_fast_ctr() can't succeed.
+         *
+         * 2. Ensures we see the result of every previous this_cpu_add() in
+         *    update_fast_ctr().
+         *
+         * 3. Ensures that if any reader has exited its critical section via
+         *    fast-path, it executes a full memory barrier before we return.
+         *    See R_W case in the comment above update_fast_ctr().
+         */
+        synchronize_sched_expedited();
+
+        /* exclude other writers, and block the new readers completely */
+        down_write(&brw->rw_sem);
+
+        /* nobody can use fast_read_ctr, move its sum into slow_read_ctr */
+        atomic_add(clear_fast_ctr(brw), &brw->slow_read_ctr);
+
+        /* wait for all readers to complete their percpu_up_read() */
+        wait_event(brw->write_waitq, !atomic_read(&brw->slow_read_ctr));
+}
+
+void percpu_up_write(struct percpu_rw_semaphore *brw)
+{
+        /* release the lock, but the readers can't use the fast-path */
+        up_write(&brw->rw_sem);
+        /*
+         * Insert the barrier before the next fast-path in down_read,
+         * see W_R case in the comment above update_fast_ctr().
+         */
+        synchronize_sched_expedited();
+        /* the last writer unblocks update_fast_ctr() */
+        atomic_dec(&brw->write_ctr);
+}
diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
new file mode 100644
index 000000000000..13b243a323fa
--- /dev/null
+++ b/kernel/locking/rtmutex-debug.c
@@ -0,0 +1,187 @@
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This code is based on the rt.c implementation in the preempt-rt tree.
+ * Portions of said code are
+ *
+ *  Copyright (C) 2004  LynuxWorks, Inc., Igor Manyilov, Bill Huey
+ *  Copyright (C) 2006  Esben Nielsen
+ *  Copyright (C) 2006  Kihon Technologies Inc.,
+ *                      Steven Rostedt <rostedt@goodmis.org>
+ *
+ * See rt.c in preempt-rt for proper credits and further information
+ */
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/syscalls.h>
+#include <linux/interrupt.h>
+#include <linux/plist.h>
+#include <linux/fs.h>
+#include <linux/debug_locks.h>
+
+#include "rtmutex_common.h"
+
+static void printk_task(struct task_struct *p)
+{
+        if (p)
+                printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
+        else
+                printk("<none>");
+}
+
+static void printk_lock(struct rt_mutex *lock, int print_owner)
+{
+        if (lock->name)
+                printk(" [%p] {%s}\n",
+                        lock, lock->name);
+        else
+                printk(" [%p] {%s:%d}\n",
+                        lock, lock->file, lock->line);
+
+        if (print_owner && rt_mutex_owner(lock)) {
+                printk(".. ->owner: %p\n", lock->owner);
+                printk(".. held by:  ");
+                printk_task(rt_mutex_owner(lock));
+                printk("\n");
+        }
+}
+
+void rt_mutex_debug_task_free(struct task_struct *task)
+{
+        DEBUG_LOCKS_WARN_ON(!plist_head_empty(&task->pi_waiters));
+        DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
+}
+
+/*
+ * We fill out the fields in the waiter to store the information about
+ * the deadlock. We print when we return. act_waiter can be NULL in
+ * case of a remove waiter operation.
+ */
+void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
+                             struct rt_mutex *lock)
+{
+        struct task_struct *task;
+
+        if (!debug_locks || detect || !act_waiter)
+                return;
+
+        task = rt_mutex_owner(act_waiter->lock);
+        if (task && task != current) {
+                act_waiter->deadlock_task_pid = get_pid(task_pid(task));
+                act_waiter->deadlock_lock = lock;
+        }
+}
+
+void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
+{
+        struct task_struct *task;
+
+        if (!waiter->deadlock_lock || !debug_locks)
+                return;
+
+        rcu_read_lock();
+        task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
+        if (!task) {
+                rcu_read_unlock();
+                return;
+        }
+
+        if (!debug_locks_off()) {
+                rcu_read_unlock();
+                return;
+        }
+
+        printk("\n============================================\n");
+        printk(  "[ BUG: circular locking deadlock detected! ]\n");
+        printk("%s\n", print_tainted());
+        printk(  "--------------------------------------------\n");
+        printk("%s/%d is deadlocking current task %s/%d\n\n",
+               task->comm, task_pid_nr(task),
+               current->comm, task_pid_nr(current));
+
+        printk("\n1) %s/%d is trying to acquire this lock:\n",
+               current->comm, task_pid_nr(current));
+        printk_lock(waiter->lock, 1);
+
+        printk("\n2) %s/%d is blocked on this lock:\n",
+                task->comm, task_pid_nr(task));
+        printk_lock(waiter->deadlock_lock, 1);
+
+        debug_show_held_locks(current);
+        debug_show_held_locks(task);
+
+        printk("\n%s/%d's [blocked] stackdump:\n\n",
+                task->comm, task_pid_nr(task));
+        show_stack(task, NULL);
+        printk("\n%s/%d's [current] stackdump:\n\n",
+                current->comm, task_pid_nr(current));
+        dump_stack();
+        debug_show_all_locks();
+        rcu_read_unlock();
+
+        printk("[ turning off deadlock detection."
+               "Please report this trace. ]\n\n");
+}
+
+void debug_rt_mutex_lock(struct rt_mutex *lock)
+{
+}
+
+void debug_rt_mutex_unlock(struct rt_mutex *lock)
+{
+        DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
+}
+
+void
+debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
+{
+}
+
+void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
+{
+        DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
+}
+
+void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
+{
+        memset(waiter, 0x11, sizeof(*waiter));
+        plist_node_init(&waiter->list_entry, MAX_PRIO);
+        plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
+        waiter->deadlock_task_pid = NULL;
+}
+
+void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
+{
+        put_pid(waiter->deadlock_task_pid);
+        DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->list_entry));
+        DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
+        memset(waiter, 0x22, sizeof(*waiter));
+}
+
+void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
+{
+        /*
+         * Make sure we are not reinitializing a held lock:
+         */
+        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+        lock->name = name;
+}
+
+void
+rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
+{
+}
+
+void rt_mutex_deadlock_account_unlock(struct task_struct *task)
+{
+}
+
diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h
new file mode 100644
index 000000000000..14193d596d78
--- /dev/null
+++ b/kernel/locking/rtmutex-debug.h
@@ -0,0 +1,33 @@
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains macros used solely by rtmutex.c. Debug version.
+ */
+
+extern void
+rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task);
+extern void rt_mutex_deadlock_account_unlock(struct task_struct *task);
+extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
+extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
+extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name);
+extern void debug_rt_mutex_lock(struct rt_mutex *lock);
+extern void debug_rt_mutex_unlock(struct rt_mutex *lock);
+extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
+                                      struct task_struct *powner);
+extern void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock);
+extern void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *waiter,
+                                    struct rt_mutex *lock);
+extern void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter);
+# define debug_rt_mutex_reset_waiter(w)                 \
+        do { (w)->deadlock_lock = NULL; } while (0)
+
+static inline int debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter,
+                                                 int detect)
+{
+        return (waiter != NULL);
+}
diff --git a/kernel/locking/rtmutex-tester.c b/kernel/locking/rtmutex-tester.c
new file mode 100644
index 000000000000..1d96dd0d93c1
--- /dev/null
+++ b/kernel/locking/rtmutex-tester.c
@@ -0,0 +1,420 @@
+/*
+ * RT-Mutex-tester: scriptable tester for rt mutexes
+ *
+ * started by Thomas Gleixner:
+ *
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ */
+#include <linux/device.h>
+#include <linux/kthread.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/freezer.h>
+#include <linux/stat.h>
+
+#include "rtmutex.h"
+
+#define MAX_RT_TEST_THREADS     8
+#define MAX_RT_TEST_MUTEXES     8
+
+static spinlock_t rttest_lock;
+static atomic_t rttest_event;
+
+struct test_thread_data {
+        int                     opcode;
+        int                     opdata;
+        int                     mutexes[MAX_RT_TEST_MUTEXES];
+        int                     event;
+        struct device           dev;
+};
+
+static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
+static struct task_struct *threads[MAX_RT_TEST_THREADS];
+static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
+
+enum test_opcodes {
+        RTTEST_NOP = 0,
+        RTTEST_SCHEDOT,         /* 1 Sched other, data = nice */
+        RTTEST_SCHEDRT,         /* 2 Sched fifo, data = prio */
+        RTTEST_LOCK,            /* 3 Lock uninterruptible, data = lockindex */
+        RTTEST_LOCKNOWAIT,      /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
+        RTTEST_LOCKINT,         /* 5 Lock interruptible, data = lockindex */
+        RTTEST_LOCKINTNOWAIT,   /* 6 Lock interruptible no wait in wakeup, data = lockindex */
+        RTTEST_LOCKCONT,        /* 7 Continue locking after the wakeup delay */
+        RTTEST_UNLOCK,          /* 8 Unlock, data = lockindex */
+        /* 9, 10 - reserved for BKL commemoration */
+        RTTEST_SIGNAL = 11,     /* 11 Signal other test thread, data = thread id */
+        RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
+        RTTEST_RESET = 99,      /* 99 Reset all pending operations */
+};
+
+static int handle_op(struct test_thread_data *td, int lockwakeup)
+{
+        int i, id, ret = -EINVAL;
+
+        switch(td->opcode) {
+
+        case RTTEST_NOP:
+                return 0;
+
+        case RTTEST_LOCKCONT:
+                td->mutexes[td->opdata] = 1;
+                td->event = atomic_add_return(1, &rttest_event);
+                return 0;
+
+        case RTTEST_RESET:
+                for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
+                        if (td->mutexes[i] == 4) {
+                                rt_mutex_unlock(&mutexes[i]);
+                                td->mutexes[i] = 0;
+                        }
+                }
+                return 0;
+
+        case RTTEST_RESETEVENT:
+                atomic_set(&rttest_event, 0);
+                return 0;
+
+        default:
+                if (lockwakeup)
+                        return ret;
+        }
+
+        switch(td->opcode) {
+
+        case RTTEST_LOCK:
+        case RTTEST_LOCKNOWAIT:
+                id = td->opdata;
+                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
+                        return ret;
+
+                td->mutexes[id] = 1;
+                td->event = atomic_add_return(1, &rttest_event);
+                rt_mutex_lock(&mutexes[id]);
+                td->event = atomic_add_return(1, &rttest_event);
+                td->mutexes[id] = 4;
+                return 0;
+
+        case RTTEST_LOCKINT:
+        case RTTEST_LOCKINTNOWAIT:
+                id = td->opdata;
+                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
+                        return ret;
+
+                td->mutexes[id] = 1;
+                td->event = atomic_add_return(1, &rttest_event);
+                ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
+                td->event = atomic_add_return(1, &rttest_event);
+                td->mutexes[id] = ret ? 0 : 4;
+                return ret ? -EINTR : 0;
+
+        case RTTEST_UNLOCK:
+                id = td->opdata;
+                if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
+                        return ret;
+
+                td->event = atomic_add_return(1, &rttest_event);
+                rt_mutex_unlock(&mutexes[id]);
+                td->event = atomic_add_return(1, &rttest_event);
+                td->mutexes[id] = 0;
+                return 0;
+
+        default:
+                break;
+        }
+        return ret;
+}
+
+/*
+ * Schedule replacement for rtsem_down(). Only called for threads with
+ * PF_MUTEX_TESTER set.
+ *
+ * This allows us to have finegrained control over the event flow.
+ *
+ */
+void schedule_rt_mutex_test(struct rt_mutex *mutex)
+{
+        int tid, op, dat;
+        struct test_thread_data *td;
+
+        /* We have to lookup the task */
+        for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
+                if (threads[tid] == current)
+                        break;
+        }
+
+        BUG_ON(tid == MAX_RT_TEST_THREADS);
+
+        td = &thread_data[tid];
+
+        op = td->opcode;
+        dat = td->opdata;
+
+        switch (op) {
+        case RTTEST_LOCK:
+        case RTTEST_LOCKINT:
+        case RTTEST_LOCKNOWAIT:
+        case RTTEST_LOCKINTNOWAIT:
+                if (mutex != &mutexes[dat])
+                        break;
+
+                if (td->mutexes[dat] != 1)
+                        break;
+
+                td->mutexes[dat] = 2;
+                td->event = atomic_add_return(1, &rttest_event);
+                break;
+
+        default:
+                break;
+        }
+
+        schedule();
+
+
+        switch (op) {
+        case RTTEST_LOCK:
+        case RTTEST_LOCKINT:
+                if (mutex != &mutexes[dat])
+                        return;
+
+                if (td->mutexes[dat] != 2)
+                        return;
+
+                td->mutexes[dat] = 3;
+                td->event = atomic_add_return(1, &rttest_event);
+                break;
+
+        case RTTEST_LOCKNOWAIT:
+        case RTTEST_LOCKINTNOWAIT:
+                if (mutex != &mutexes[dat])
+                        return;
+
+                if (td->mutexes[dat] != 2)
+                        return;
+
+                td->mutexes[dat] = 1;
+                td->event = atomic_add_return(1, &rttest_event);
+                return;
+
+        default:
+                return;
+        }
+
+        td->opcode = 0;
+
+        for (;;) {
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                if (td->opcode > 0) {
+                        int ret;
+
+                        set_current_state(TASK_RUNNING);
+                        ret = handle_op(td, 1);
+                        set_current_state(TASK_INTERRUPTIBLE);
+                        if (td->opcode == RTTEST_LOCKCONT)
+                                break;
+                        td->opcode = ret;
+                }
+
+                /* Wait for the next command to be executed */
+                schedule();
+        }
+
+        /* Restore previous command and data */
+        td->opcode = op;
+        td->opdata = dat;
+}
+
+static int test_func(void *data)
+{
+        struct test_thread_data *td = data;
+        int ret;
+
+        current->flags |= PF_MUTEX_TESTER;
+        set_freezable();
+        allow_signal(SIGHUP);
+
+        for(;;) {
+
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                if (td->opcode > 0) {
+                        set_current_state(TASK_RUNNING);
+                        ret = handle_op(td, 0);
+                        set_current_state(TASK_INTERRUPTIBLE);
+                        td->opcode = ret;
+                }
+
+                /* Wait for the next command to be executed */
+                schedule();
+                try_to_freeze();
+
+                if (signal_pending(current))
+                        flush_signals(current);
+
+                if(kthread_should_stop())
+                        break;
+        }
+        return 0;
+}
+
+/**
+ * sysfs_test_command - interface for test commands
+ * @dev:        thread reference
+ * @buf:        command for actual step
+ * @count:      length of buffer
+ *
+ * command syntax:
+ *
+ * opcode:data
+ */
+static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr,
+                                  const char *buf, size_t count)
+{
+        struct sched_param schedpar;
+        struct test_thread_data *td;
+        char cmdbuf[32];
+        int op, dat, tid, ret;
+
+        td = container_of(dev, struct test_thread_data, dev);
+        tid = td->dev.id;
+
+        /* strings from sysfs write are not 0 terminated! */
+        if (count >= sizeof(cmdbuf))
+                return -EINVAL;
+
+        /* strip of \n: */
+        if (buf[count-1] == '\n')
+                count--;
+        if (count < 1)
+                return -EINVAL;
+
+        memcpy(cmdbuf, buf, count);
+        cmdbuf[count] = 0;
+
+        if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
+                return -EINVAL;
+
+        switch (op) {
+        case RTTEST_SCHEDOT:
+                schedpar.sched_priority = 0;
+                ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
+                if (ret)
+                        return ret;
+                set_user_nice(current, 0);
+                break;
+
+        case RTTEST_SCHEDRT:
+                schedpar.sched_priority = dat;
+                ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
+                if (ret)
+                        return ret;
+                break;
+
+        case RTTEST_SIGNAL:
+                send_sig(SIGHUP, threads[tid], 0);
+                break;
+
+        default:
+                if (td->opcode > 0)
+                        return -EBUSY;
+                td->opdata = dat;
+                td->opcode = op;
+                wake_up_process(threads[tid]);
+        }
+
+        return count;
+}
+
+/**
+ * sysfs_test_status - sysfs interface for rt tester
+ * @dev:        thread to query
+ * @buf:        char buffer to be filled with thread status info
+ */
+static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr,
+                                 char *buf)
+{
+        struct test_thread_data *td;
+        struct task_struct *tsk;
+        char *curr = buf;
+        int i;
+
+        td = container_of(dev, struct test_thread_data, dev);
+        tsk = threads[td->dev.id];
+
+        spin_lock(&rttest_lock);
+
+        curr += sprintf(curr,
+                "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
+                td->opcode, td->event, tsk->state,
+                        (MAX_RT_PRIO - 1) - tsk->prio,
+                        (MAX_RT_PRIO - 1) - tsk->normal_prio,
+                tsk->pi_blocked_on);
+
+        for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
+                curr += sprintf(curr, "%d", td->mutexes[i]);
+
+        spin_unlock(&rttest_lock);
+
+        curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
+                        mutexes[td->dev.id].owner);
+
+        return curr - buf;
+}
+
+static DEVICE_ATTR(status, S_IRUSR, sysfs_test_status, NULL);
+static DEVICE_ATTR(command, S_IWUSR, NULL, sysfs_test_command);
+
+static struct bus_type rttest_subsys = {
+        .name = "rttest",
+        .dev_name = "rttest",
+};
+
+static int init_test_thread(int id)
+{
+        thread_data[id].dev.bus = &rttest_subsys;
+        thread_data[id].dev.id = id;
+
+        threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
+        if (IS_ERR(threads[id]))
+                return PTR_ERR(threads[id]);
+
+        return device_register(&thread_data[id].dev);
+}
+
+static int init_rttest(void)
+{
+        int ret, i;
+
+        spin_lock_init(&rttest_lock);
+
+        for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
+                rt_mutex_init(&mutexes[i]);
+
+        ret = subsys_system_register(&rttest_subsys, NULL);
+        if (ret)
+                return ret;
+
+        for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
+                ret = init_test_thread(i);
+                if (ret)
+                        break;
+                ret = device_create_file(&thread_data[i].dev, &dev_attr_status);
+                if (ret)
+                        break;
+                ret = device_create_file(&thread_data[i].dev, &dev_attr_command);
+                if (ret)
+                        break;
+        }
+
+        printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
+
+        return ret;
+}
+
+device_initcall(init_rttest);
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
new file mode 100644
index 000000000000..0dd6aec1cb6a
--- /dev/null
+++ b/kernel/locking/rtmutex.c
@@ -0,0 +1,1060 @@
+/*
+ * RT-Mutexes: simple blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner.
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *  Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt
+ *  Copyright (C) 2006 Esben Nielsen
+ *
+ *  See Documentation/rt-mutex-design.txt for details.
+ */
+#include <linux/spinlock.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/timer.h>
+
+#include "rtmutex_common.h"
+
+/*
+ * lock->owner state tracking:
+ *
+ * lock->owner holds the task_struct pointer of the owner. Bit 0
+ * is used to keep track of the "lock has waiters" state.
+ *
+ * owner        bit0
+ * NULL         0       lock is free (fast acquire possible)
+ * NULL         1       lock is free and has waiters and the top waiter
+ *                              is going to take the lock*
+ * taskpointer  0       lock is held (fast release possible)
+ * taskpointer  1       lock is held and has waiters**
+ *
+ * The fast atomic compare exchange based acquire and release is only
+ * possible when bit 0 of lock->owner is 0.
+ *
+ * (*) It also can be a transitional state when grabbing the lock
+ * with ->wait_lock is held. To prevent any fast path cmpxchg to the lock,
+ * we need to set the bit0 before looking at the lock, and the owner may be
+ * NULL in this small time, hence this can be a transitional state.
+ *
+ * (**) There is a small time when bit 0 is set but there are no
+ * waiters. This can happen when grabbing the lock in the slow path.
+ * To prevent a cmpxchg of the owner releasing the lock, we need to
+ * set this bit before looking at the lock.
+ */
+
+static void
+rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner)
+{
+        unsigned long val = (unsigned long)owner;
+
+        if (rt_mutex_has_waiters(lock))
+                val |= RT_MUTEX_HAS_WAITERS;
+
+        lock->owner = (struct task_struct *)val;
+}
+
+static inline void clear_rt_mutex_waiters(struct rt_mutex *lock)
+{
+        lock->owner = (struct task_struct *)
+                        ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
+}
+
+static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
+{
+        if (!rt_mutex_has_waiters(lock))
+                clear_rt_mutex_waiters(lock);
+}
+
+/*
+ * We can speed up the acquire/release, if the architecture
+ * supports cmpxchg and if there's no debugging state to be set up
+ */
+#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES)
+# define rt_mutex_cmpxchg(l,c,n)        (cmpxchg(&l->owner, c, n) == c)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+        unsigned long owner, *p = (unsigned long *) &lock->owner;
+
+        do {
+                owner = *p;
+        } while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner);
+}
+#else
+# define rt_mutex_cmpxchg(l,c,n)        (0)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+        lock->owner = (struct task_struct *)
+                        ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
+}
+#endif
+
+/*
+ * Calculate task priority from the waiter list priority
+ *
+ * Return task->normal_prio when the waiter list is empty or when
+ * the waiter is not allowed to do priority boosting
+ */
+int rt_mutex_getprio(struct task_struct *task)
+{
+        if (likely(!task_has_pi_waiters(task)))
+                return task->normal_prio;
+
+        return min(task_top_pi_waiter(task)->pi_list_entry.prio,
+                   task->normal_prio);
+}
+
+/*
+ * Adjust the priority of a task, after its pi_waiters got modified.
+ *
+ * This can be both boosting and unboosting. task->pi_lock must be held.
+ */
+static void __rt_mutex_adjust_prio(struct task_struct *task)
+{
+        int prio = rt_mutex_getprio(task);
+
+        if (task->prio != prio)
+                rt_mutex_setprio(task, prio);
+}
+
+/*
+ * Adjust task priority (undo boosting). Called from the exit path of
+ * rt_mutex_slowunlock() and rt_mutex_slowlock().
+ *
+ * (Note: We do this outside of the protection of lock->wait_lock to
+ * allow the lock to be taken while or before we readjust the priority
+ * of task. We do not use the spin_xx_mutex() variants here as we are
+ * outside of the debug path.)
+ */
+static void rt_mutex_adjust_prio(struct task_struct *task)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&task->pi_lock, flags);
+        __rt_mutex_adjust_prio(task);
+        raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+}
+
+/*
+ * Max number of times we'll walk the boosting chain:
+ */
+int max_lock_depth = 1024;
+
+/*
+ * Adjust the priority chain. Also used for deadlock detection.
+ * Decreases task's usage by one - may thus free the task.
+ *
+ * @task: the task owning the mutex (owner) for which a chain walk is probably
+ *        needed
+ * @deadlock_detect: do we have to carry out deadlock detection?
+ * @orig_lock: the mutex (can be NULL if we are walking the chain to recheck
+ *             things for a task that has just got its priority adjusted, and
+ *             is waiting on a mutex)
+ * @orig_waiter: rt_mutex_waiter struct for the task that has just donated
+ *               its priority to the mutex owner (can be NULL in the case
+ *               depicted above or if the top waiter is gone away and we are
+ *               actually deboosting the owner)
+ * @top_task: the current top waiter
+ *
+ * Returns 0 or -EDEADLK.
+ */
+static int rt_mutex_adjust_prio_chain(struct task_struct *task,
+                                      int deadlock_detect,
+                                      struct rt_mutex *orig_lock,
+                                      struct rt_mutex_waiter *orig_waiter,
+                                      struct task_struct *top_task)
+{
+        struct rt_mutex *lock;
+        struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter;
+        int detect_deadlock, ret = 0, depth = 0;
+        unsigned long flags;
+
+        detect_deadlock = debug_rt_mutex_detect_deadlock(orig_waiter,
+                                                         deadlock_detect);
+
+        /*
+         * The (de)boosting is a step by step approach with a lot of
+         * pitfalls. We want this to be preemptible and we want hold a
+         * maximum of two locks per step. So we have to check
+         * carefully whether things change under us.
+         */
+ again:
+        if (++depth > max_lock_depth) {
+                static int prev_max;
+
+                /*
+                 * Print this only once. If the admin changes the limit,
+                 * print a new message when reaching the limit again.
+                 */
+                if (prev_max != max_lock_depth) {
+                        prev_max = max_lock_depth;
+                        printk(KERN_WARNING "Maximum lock depth %d reached "
+                               "task: %s (%d)\n", max_lock_depth,
+                               top_task->comm, task_pid_nr(top_task));
+                }
+                put_task_struct(task);
+
+                return deadlock_detect ? -EDEADLK : 0;
+        }
+ retry:
+        /*
+         * Task can not go away as we did a get_task() before !
+         */
+        raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+        waiter = task->pi_blocked_on;
+        /*
+         * Check whether the end of the boosting chain has been
+         * reached or the state of the chain has changed while we
+         * dropped the locks.
+         */
+        if (!waiter)
+                goto out_unlock_pi;
+
+        /*
+         * Check the orig_waiter state. After we dropped the locks,
+         * the previous owner of the lock might have released the lock.
+         */
+        if (orig_waiter && !rt_mutex_owner(orig_lock))
+                goto out_unlock_pi;
+
+        /*
+         * Drop out, when the task has no waiters. Note,
+         * top_waiter can be NULL, when we are in the deboosting
+         * mode!
+         */
+        if (top_waiter && (!task_has_pi_waiters(task) ||
+                           top_waiter != task_top_pi_waiter(task)))
+                goto out_unlock_pi;
+
+        /*
+         * When deadlock detection is off then we check, if further
+         * priority adjustment is necessary.
+         */
+        if (!detect_deadlock && waiter->list_entry.prio == task->prio)
+                goto out_unlock_pi;
+
+        lock = waiter->lock;
+        if (!raw_spin_trylock(&lock->wait_lock)) {
+                raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+                cpu_relax();
+                goto retry;
+        }
+
+        /* Deadlock detection */
+        if (lock == orig_lock || rt_mutex_owner(lock) == top_task) {
+                debug_rt_mutex_deadlock(deadlock_detect, orig_waiter, lock);
+                raw_spin_unlock(&lock->wait_lock);
+                ret = deadlock_detect ? -EDEADLK : 0;
+                goto out_unlock_pi;
+        }
+
+        top_waiter = rt_mutex_top_waiter(lock);
+
+        /* Requeue the waiter */
+        plist_del(&waiter->list_entry, &lock->wait_list);
+        waiter->list_entry.prio = task->prio;
+        plist_add(&waiter->list_entry, &lock->wait_list);
+
+        /* Release the task */
+        raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+        if (!rt_mutex_owner(lock)) {
+                /*
+                 * If the requeue above changed the top waiter, then we need
+                 * to wake the new top waiter up to try to get the lock.
+                 */
+
+                if (top_waiter != rt_mutex_top_waiter(lock))
+                        wake_up_process(rt_mutex_top_waiter(lock)->task);
+                raw_spin_unlock(&lock->wait_lock);
+                goto out_put_task;
+        }
+        put_task_struct(task);
+
+        /* Grab the next task */
+        task = rt_mutex_owner(lock);
+        get_task_struct(task);
+        raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+        if (waiter == rt_mutex_top_waiter(lock)) {
+                /* Boost the owner */
+                plist_del(&top_waiter->pi_list_entry, &task->pi_waiters);
+                waiter->pi_list_entry.prio = waiter->list_entry.prio;
+                plist_add(&waiter->pi_list_entry, &task->pi_waiters);
+                __rt_mutex_adjust_prio(task);
+
+        } else if (top_waiter == waiter) {
+                /* Deboost the owner */
+                plist_del(&waiter->pi_list_entry, &task->pi_waiters);
+                waiter = rt_mutex_top_waiter(lock);
+                waiter->pi_list_entry.prio = waiter->list_entry.prio;
+                plist_add(&waiter->pi_list_entry, &task->pi_waiters);
+                __rt_mutex_adjust_prio(task);
+        }
+
+        raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+        top_waiter = rt_mutex_top_waiter(lock);
+        raw_spin_unlock(&lock->wait_lock);
+
+        if (!detect_deadlock && waiter != top_waiter)
+                goto out_put_task;
+
+        goto again;
+
+ out_unlock_pi:
+        raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+ out_put_task:
+        put_task_struct(task);
+
+        return ret;
+}
+
+/*
+ * Try to take an rt-mutex
+ *
+ * Must be called with lock->wait_lock held.
+ *
+ * @lock:   the lock to be acquired.
+ * @task:   the task which wants to acquire the lock
+ * @waiter: the waiter that is queued to the lock's wait list. (could be NULL)
+ */
+static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
+                struct rt_mutex_waiter *waiter)
+{
+        /*
+         * We have to be careful here if the atomic speedups are
+         * enabled, such that, when
+         *  - no other waiter is on the lock
+         *  - the lock has been released since we did the cmpxchg
+         * the lock can be released or taken while we are doing the
+         * checks and marking the lock with RT_MUTEX_HAS_WAITERS.
+         *
+         * The atomic acquire/release aware variant of
+         * mark_rt_mutex_waiters uses a cmpxchg loop. After setting
+         * the WAITERS bit, the atomic release / acquire can not
+         * happen anymore and lock->wait_lock protects us from the
+         * non-atomic case.
+         *
+         * Note, that this might set lock->owner =
+         * RT_MUTEX_HAS_WAITERS in the case the lock is not contended
+         * any more. This is fixed up when we take the ownership.
+         * This is the transitional state explained at the top of this file.
+         */
+        mark_rt_mutex_waiters(lock);
+
+        if (rt_mutex_owner(lock))
+                return 0;
+
+        /*
+         * It will get the lock because of one of these conditions:
+         * 1) there is no waiter
+         * 2) higher priority than waiters
+         * 3) it is top waiter
+         */
+        if (rt_mutex_has_waiters(lock)) {
+                if (task->prio >= rt_mutex_top_waiter(lock)->list_entry.prio) {
+                        if (!waiter || waiter != rt_mutex_top_waiter(lock))
+                                return 0;
+                }
+        }
+
+        if (waiter || rt_mutex_has_waiters(lock)) {
+                unsigned long flags;
+                struct rt_mutex_waiter *top;
+
+                raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+                /* remove the queued waiter. */
+                if (waiter) {
+                        plist_del(&waiter->list_entry, &lock->wait_list);
+                        task->pi_blocked_on = NULL;
+                }
+
+                /*
+                 * We have to enqueue the top waiter(if it exists) into
+                 * task->pi_waiters list.
+                 */
+                if (rt_mutex_has_waiters(lock)) {
+                        top = rt_mutex_top_waiter(lock);
+                        top->pi_list_entry.prio = top->list_entry.prio;
+                        plist_add(&top->pi_list_entry, &task->pi_waiters);
+                }
+                raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+        }
+
+        /* We got the lock. */
+        debug_rt_mutex_lock(lock);
+
+        rt_mutex_set_owner(lock, task);
+
+        rt_mutex_deadlock_account_lock(lock, task);
+
+        return 1;
+}
+
+/*
+ * Task blocks on lock.
+ *
+ * Prepare waiter and propagate pi chain
+ *
+ * This must be called with lock->wait_lock held.
+ */
+static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
+                                   struct rt_mutex_waiter *waiter,
+                                   struct task_struct *task,
+                                   int detect_deadlock)
+{
+        struct task_struct *owner = rt_mutex_owner(lock);
+        struct rt_mutex_waiter *top_waiter = waiter;
+        unsigned long flags;
+        int chain_walk = 0, res;
+
+        raw_spin_lock_irqsave(&task->pi_lock, flags);
+        __rt_mutex_adjust_prio(task);
+        waiter->task = task;
+        waiter->lock = lock;
+        plist_node_init(&waiter->list_entry, task->prio);
+        plist_node_init(&waiter->pi_list_entry, task->prio);
+
+        /* Get the top priority waiter on the lock */
+        if (rt_mutex_has_waiters(lock))
+                top_waiter = rt_mutex_top_waiter(lock);
+        plist_add(&waiter->list_entry, &lock->wait_list);
+
+        task->pi_blocked_on = waiter;
+
+        raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+        if (!owner)
+                return 0;
+
+        if (waiter == rt_mutex_top_waiter(lock)) {
+                raw_spin_lock_irqsave(&owner->pi_lock, flags);
+                plist_del(&top_waiter->pi_list_entry, &owner->pi_waiters);
+                plist_add(&waiter->pi_list_entry, &owner->pi_waiters);
+
+                __rt_mutex_adjust_prio(owner);
+                if (owner->pi_blocked_on)
+                        chain_walk = 1;
+                raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
+        }
+        else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock))
+                chain_walk = 1;
+
+        if (!chain_walk)
+                return 0;
+
+        /*
+         * The owner can't disappear while holding a lock,
+         * so the owner struct is protected by wait_lock.
+         * Gets dropped in rt_mutex_adjust_prio_chain()!
+         */
+        get_task_struct(owner);
+
+        raw_spin_unlock(&lock->wait_lock);
+
+        res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock, waiter,
+                                         task);
+
+        raw_spin_lock(&lock->wait_lock);
+
+        return res;
+}
+
+/*
+ * Wake up the next waiter on the lock.
+ *
+ * Remove the top waiter from the current tasks waiter list and wake it up.
+ *
+ * Called with lock->wait_lock held.
+ */
+static void wakeup_next_waiter(struct rt_mutex *lock)
+{
+        struct rt_mutex_waiter *waiter;
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&current->pi_lock, flags);
+
+        waiter = rt_mutex_top_waiter(lock);
+
+        /*
+         * Remove it from current->pi_waiters. We do not adjust a
+         * possible priority boost right now. We execute wakeup in the
+         * boosted mode and go back to normal after releasing
+         * lock->wait_lock.
+         */
+        plist_del(&waiter->pi_list_entry, &current->pi_waiters);
+
+        rt_mutex_set_owner(lock, NULL);
+
+        raw_spin_unlock_irqrestore(&current->pi_lock, flags);
+
+        wake_up_process(waiter->task);
+}
+
+/*
+ * Remove a waiter from a lock and give up
+ *
+ * Must be called with lock->wait_lock held and
+ * have just failed to try_to_take_rt_mutex().
+ */
+static void remove_waiter(struct rt_mutex *lock,
+                          struct rt_mutex_waiter *waiter)
+{
+        int first = (waiter == rt_mutex_top_waiter(lock));
+        struct task_struct *owner = rt_mutex_owner(lock);
+        unsigned long flags;
+        int chain_walk = 0;
+
+        raw_spin_lock_irqsave(&current->pi_lock, flags);
+        plist_del(&waiter->list_entry, &lock->wait_list);
+        current->pi_blocked_on = NULL;
+        raw_spin_unlock_irqrestore(&current->pi_lock, flags);
+
+        if (!owner)
+                return;
+
+        if (first) {
+
+                raw_spin_lock_irqsave(&owner->pi_lock, flags);
+
+                plist_del(&waiter->pi_list_entry, &owner->pi_waiters);
+
+                if (rt_mutex_has_waiters(lock)) {
+                        struct rt_mutex_waiter *next;
+
+                        next = rt_mutex_top_waiter(lock);
+                        plist_add(&next->pi_list_entry, &owner->pi_waiters);
+                }
+                __rt_mutex_adjust_prio(owner);
+
+                if (owner->pi_blocked_on)
+                        chain_walk = 1;
+
+                raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
+        }
+
+        WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
+
+        if (!chain_walk)
+                return;
+
+        /* gets dropped in rt_mutex_adjust_prio_chain()! */
+        get_task_struct(owner);
+
+        raw_spin_unlock(&lock->wait_lock);
+
+        rt_mutex_adjust_prio_chain(owner, 0, lock, NULL, current);
+
+        raw_spin_lock(&lock->wait_lock);
+}
+
+/*
+ * Recheck the pi chain, in case we got a priority setting
+ *
+ * Called from sched_setscheduler
+ */
+void rt_mutex_adjust_pi(struct task_struct *task)
+{
+        struct rt_mutex_waiter *waiter;
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+        waiter = task->pi_blocked_on;
+        if (!waiter || waiter->list_entry.prio == task->prio) {
+                raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+                return;
+        }
+
+        raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+        /* gets dropped in rt_mutex_adjust_prio_chain()! */
+        get_task_struct(task);
+        rt_mutex_adjust_prio_chain(task, 0, NULL, NULL, task);
+}
+
+/**
+ * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
+ * @lock:                the rt_mutex to take
+ * @state:               the state the task should block in (TASK_INTERRUPTIBLE
+ *                       or TASK_UNINTERRUPTIBLE)
+ * @timeout:             the pre-initialized and started timer, or NULL for none
+ * @waiter:              the pre-initialized rt_mutex_waiter
+ *
+ * lock->wait_lock must be held by the caller.
+ */
+static int __sched
+__rt_mutex_slowlock(struct rt_mutex *lock, int state,
+                    struct hrtimer_sleeper *timeout,
+                    struct rt_mutex_waiter *waiter)
+{
+        int ret = 0;
+
+        for (;;) {
+                /* Try to acquire the lock: */
+                if (try_to_take_rt_mutex(lock, current, waiter))
+                        break;
+
+                /*
+                 * TASK_INTERRUPTIBLE checks for signals and
+                 * timeout. Ignored otherwise.
+                 */
+                if (unlikely(state == TASK_INTERRUPTIBLE)) {
+                        /* Signal pending? */
+                        if (signal_pending(current))
+                                ret = -EINTR;
+                        if (timeout && !timeout->task)
+                                ret = -ETIMEDOUT;
+                        if (ret)
+                                break;
+                }
+
+                raw_spin_unlock(&lock->wait_lock);
+
+                debug_rt_mutex_print_deadlock(waiter);
+
+                schedule_rt_mutex(lock);
+
+                raw_spin_lock(&lock->wait_lock);
+                set_current_state(state);
+        }
+
+        return ret;
+}
+
+/*
+ * Slow path lock function:
+ */
+static int __sched
+rt_mutex_slowlock(struct rt_mutex *lock, int state,
+                  struct hrtimer_sleeper *timeout,
+                  int detect_deadlock)
+{
+        struct rt_mutex_waiter waiter;
+        int ret = 0;
+
+        debug_rt_mutex_init_waiter(&waiter);
+
+        raw_spin_lock(&lock->wait_lock);
+
+        /* Try to acquire the lock again: */
+        if (try_to_take_rt_mutex(lock, current, NULL)) {
+                raw_spin_unlock(&lock->wait_lock);
+                return 0;
+        }
+
+        set_current_state(state);
+
+        /* Setup the timer, when timeout != NULL */
+        if (unlikely(timeout)) {
+                hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS);
+                if (!hrtimer_active(&timeout->timer))
+                        timeout->task = NULL;
+        }
+
+        ret = task_blocks_on_rt_mutex(lock, &waiter, current, detect_deadlock);
+
+        if (likely(!ret))
+                ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
+
+        set_current_state(TASK_RUNNING);
+
+        if (unlikely(ret))
+                remove_waiter(lock, &waiter);
+
+        /*
+         * try_to_take_rt_mutex() sets the waiter bit
+         * unconditionally. We might have to fix that up.
+         */
+        fixup_rt_mutex_waiters(lock);
+
+        raw_spin_unlock(&lock->wait_lock);
+
+        /* Remove pending timer: */
+        if (unlikely(timeout))
+                hrtimer_cancel(&timeout->timer);
+
+        debug_rt_mutex_free_waiter(&waiter);
+
+        return ret;
+}
+
+/*
+ * Slow path try-lock function:
+ */
+static inline int
+rt_mutex_slowtrylock(struct rt_mutex *lock)
+{
+        int ret = 0;
+
+        raw_spin_lock(&lock->wait_lock);
+
+        if (likely(rt_mutex_owner(lock) != current)) {
+
+                ret = try_to_take_rt_mutex(lock, current, NULL);
+                /*
+                 * try_to_take_rt_mutex() sets the lock waiters
+                 * bit unconditionally. Clean this up.
+                 */
+                fixup_rt_mutex_waiters(lock);
+        }
+
+        raw_spin_unlock(&lock->wait_lock);
+
+        return ret;
+}
+
+/*
+ * Slow path to release a rt-mutex:
+ */
+static void __sched
+rt_mutex_slowunlock(struct rt_mutex *lock)
+{
+        raw_spin_lock(&lock->wait_lock);
+
+        debug_rt_mutex_unlock(lock);
+
+        rt_mutex_deadlock_account_unlock(current);
+
+        if (!rt_mutex_has_waiters(lock)) {
+                lock->owner = NULL;
+                raw_spin_unlock(&lock->wait_lock);
+                return;
+        }
+
+        wakeup_next_waiter(lock);
+
+        raw_spin_unlock(&lock->wait_lock);
+
+        /* Undo pi boosting if necessary: */
+        rt_mutex_adjust_prio(current);
+}
+
+/*
+ * debug aware fast / slowpath lock,trylock,unlock
+ *
+ * The atomic acquire/release ops are compiled away, when either the
+ * architecture does not support cmpxchg or when debugging is enabled.
+ */
+static inline int
+rt_mutex_fastlock(struct rt_mutex *lock, int state,
+                  int detect_deadlock,
+                  int (*slowfn)(struct rt_mutex *lock, int state,
+                                struct hrtimer_sleeper *timeout,
+                                int detect_deadlock))
+{
+        if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+                rt_mutex_deadlock_account_lock(lock, current);
+                return 0;
+        } else
+                return slowfn(lock, state, NULL, detect_deadlock);
+}
+
+static inline int
+rt_mutex_timed_fastlock(struct rt_mutex *lock, int state,
+                        struct hrtimer_sleeper *timeout, int detect_deadlock,
+                        int (*slowfn)(struct rt_mutex *lock, int state,
+                                      struct hrtimer_sleeper *timeout,
+                                      int detect_deadlock))
+{
+        if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+                rt_mutex_deadlock_account_lock(lock, current);
+                return 0;
+        } else
+                return slowfn(lock, state, timeout, detect_deadlock);
+}
+
+static inline int
+rt_mutex_fasttrylock(struct rt_mutex *lock,
+                     int (*slowfn)(struct rt_mutex *lock))
+{
+        if (likely(rt_mutex_cmpxchg(lock, NULL, current))) {
+                rt_mutex_deadlock_account_lock(lock, current);
+                return 1;
+        }
+        return slowfn(lock);
+}
+
+static inline void
+rt_mutex_fastunlock(struct rt_mutex *lock,
+                    void (*slowfn)(struct rt_mutex *lock))
+{
+        if (likely(rt_mutex_cmpxchg(lock, current, NULL)))
+                rt_mutex_deadlock_account_unlock(current);
+        else
+                slowfn(lock);
+}
+
+/**
+ * rt_mutex_lock - lock a rt_mutex
+ *
+ * @lock: the rt_mutex to be locked
+ */
+void __sched rt_mutex_lock(struct rt_mutex *lock)
+{
+        might_sleep();
+
+        rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, 0, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_lock);
+
+/**
+ * rt_mutex_lock_interruptible - lock a rt_mutex interruptible
+ *
+ * @lock:               the rt_mutex to be locked
+ * @detect_deadlock:    deadlock detection on/off
+ *
+ * Returns:
+ *  0           on success
+ * -EINTR       when interrupted by a signal
+ * -EDEADLK     when the lock would deadlock (when deadlock detection is on)
+ */
+int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock,
+                                                 int detect_deadlock)
+{
+        might_sleep();
+
+        return rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE,
+                                 detect_deadlock, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
+
+/**
+ * rt_mutex_timed_lock - lock a rt_mutex interruptible
+ *                      the timeout structure is provided
+ *                      by the caller
+ *
+ * @lock:               the rt_mutex to be locked
+ * @timeout:            timeout structure or NULL (no timeout)
+ * @detect_deadlock:    deadlock detection on/off
+ *
+ * Returns:
+ *  0           on success
+ * -EINTR       when interrupted by a signal
+ * -ETIMEDOUT   when the timeout expired
+ * -EDEADLK     when the lock would deadlock (when deadlock detection is on)
+ */
+int
+rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout,
+                    int detect_deadlock)
+{
+        might_sleep();
+
+        return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
+                                       detect_deadlock, rt_mutex_slowlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
+
+/**
+ * rt_mutex_trylock - try to lock a rt_mutex
+ *
+ * @lock:       the rt_mutex to be locked
+ *
+ * Returns 1 on success and 0 on contention
+ */
+int __sched rt_mutex_trylock(struct rt_mutex *lock)
+{
+        return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_trylock);
+
+/**
+ * rt_mutex_unlock - unlock a rt_mutex
+ *
+ * @lock: the rt_mutex to be unlocked
+ */
+void __sched rt_mutex_unlock(struct rt_mutex *lock)
+{
+        rt_mutex_fastunlock(lock, rt_mutex_slowunlock);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_unlock);
+
+/**
+ * rt_mutex_destroy - mark a mutex unusable
+ * @lock: the mutex to be destroyed
+ *
+ * This function marks the mutex uninitialized, and any subsequent
+ * use of the mutex is forbidden. The mutex must not be locked when
+ * this function is called.
+ */
+void rt_mutex_destroy(struct rt_mutex *lock)
+{
+        WARN_ON(rt_mutex_is_locked(lock));
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+        lock->magic = NULL;
+#endif
+}
+
+EXPORT_SYMBOL_GPL(rt_mutex_destroy);
+
+/**
+ * __rt_mutex_init - initialize the rt lock
+ *
+ * @lock: the rt lock to be initialized
+ *
+ * Initialize the rt lock to unlocked state.
+ *
+ * Initializing of a locked rt lock is not allowed
+ */
+void __rt_mutex_init(struct rt_mutex *lock, const char *name)
+{
+        lock->owner = NULL;
+        raw_spin_lock_init(&lock->wait_lock);
+        plist_head_init(&lock->wait_list);
+
+        debug_rt_mutex_init(lock, name);
+}
+EXPORT_SYMBOL_GPL(__rt_mutex_init);
+
+/**
+ * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
+ *                              proxy owner
+ *
+ * @lock:       the rt_mutex to be locked
+ * @proxy_owner:the task to set as owner
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+                                struct task_struct *proxy_owner)
+{
+        __rt_mutex_init(lock, NULL);
+        debug_rt_mutex_proxy_lock(lock, proxy_owner);
+        rt_mutex_set_owner(lock, proxy_owner);
+        rt_mutex_deadlock_account_lock(lock, proxy_owner);
+}
+
+/**
+ * rt_mutex_proxy_unlock - release a lock on behalf of owner
+ *
+ * @lock:       the rt_mutex to be locked
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+void rt_mutex_proxy_unlock(struct rt_mutex *lock,
+                           struct task_struct *proxy_owner)
+{
+        debug_rt_mutex_proxy_unlock(lock);
+        rt_mutex_set_owner(lock, NULL);
+        rt_mutex_deadlock_account_unlock(proxy_owner);
+}
+
+/**
+ * rt_mutex_start_proxy_lock() - Start lock acquisition for another task
+ * @lock:               the rt_mutex to take
+ * @waiter:             the pre-initialized rt_mutex_waiter
+ * @task:               the task to prepare
+ * @detect_deadlock:    perform deadlock detection (1) or not (0)
+ *
+ * Returns:
+ *  0 - task blocked on lock
+ *  1 - acquired the lock for task, caller should wake it up
+ * <0 - error
+ *
+ * Special API call for FUTEX_REQUEUE_PI support.
+ */
+int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+                              struct rt_mutex_waiter *waiter,
+                              struct task_struct *task, int detect_deadlock)
+{
+        int ret;
+
+        raw_spin_lock(&lock->wait_lock);
+
+        if (try_to_take_rt_mutex(lock, task, NULL)) {
+                raw_spin_unlock(&lock->wait_lock);
+                return 1;
+        }
+
+        ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock);
+
+        if (ret && !rt_mutex_owner(lock)) {
+                /*
+                 * Reset the return value. We might have
+                 * returned with -EDEADLK and the owner
+                 * released the lock while we were walking the
+                 * pi chain.  Let the waiter sort it out.
+                 */
+                ret = 0;
+        }
+
+        if (unlikely(ret))
+                remove_waiter(lock, waiter);
+
+        raw_spin_unlock(&lock->wait_lock);
+
+        debug_rt_mutex_print_deadlock(waiter);
+
+        return ret;
+}
+
+/**
+ * rt_mutex_next_owner - return the next owner of the lock
+ *
+ * @lock: the rt lock query
+ *
+ * Returns the next owner of the lock or NULL
+ *
+ * Caller has to serialize against other accessors to the lock
+ * itself.
+ *
+ * Special API call for PI-futex support
+ */
+struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
+{
+        if (!rt_mutex_has_waiters(lock))
+                return NULL;
+
+        return rt_mutex_top_waiter(lock)->task;
+}
+
+/**
+ * rt_mutex_finish_proxy_lock() - Complete lock acquisition
+ * @lock:               the rt_mutex we were woken on
+ * @to:                 the timeout, null if none. hrtimer should already have
+ *                      been started.
+ * @waiter:             the pre-initialized rt_mutex_waiter
+ * @detect_deadlock:    perform deadlock detection (1) or not (0)
+ *
+ * Complete the lock acquisition started our behalf by another thread.
+ *
+ * Returns:
+ *  0 - success
+ * <0 - error, one of -EINTR, -ETIMEDOUT, or -EDEADLK
+ *
+ * Special API call for PI-futex requeue support
+ */
+int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
+                               struct hrtimer_sleeper *to,
+                               struct rt_mutex_waiter *waiter,
+                               int detect_deadlock)
+{
+        int ret;
+
+        raw_spin_lock(&lock->wait_lock);
+
+        set_current_state(TASK_INTERRUPTIBLE);
+
+        ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
+
+        set_current_state(TASK_RUNNING);
+
+        if (unlikely(ret))
+                remove_waiter(lock, waiter);
+
+        /*
+         * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
+         * have to fix that up.
+         */
+        fixup_rt_mutex_waiters(lock);
+
+        raw_spin_unlock(&lock->wait_lock);
+
+        return ret;
+}
diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h
new file mode 100644
index 000000000000..a1a1dd06421d
--- /dev/null
+++ b/kernel/locking/rtmutex.h
@@ -0,0 +1,26 @@
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains macros used solely by rtmutex.c.
+ * Non-debug version.
+ */
+
+#define rt_mutex_deadlock_check(l)                      (0)
+#define rt_mutex_deadlock_account_lock(m, t)            do { } while (0)
+#define rt_mutex_deadlock_account_unlock(l)             do { } while (0)
+#define debug_rt_mutex_init_waiter(w)                   do { } while (0)
+#define debug_rt_mutex_free_waiter(w)                   do { } while (0)
+#define debug_rt_mutex_lock(l)                          do { } while (0)
+#define debug_rt_mutex_proxy_lock(l,p)                  do { } while (0)
+#define debug_rt_mutex_proxy_unlock(l)                  do { } while (0)
+#define debug_rt_mutex_unlock(l)                        do { } while (0)
+#define debug_rt_mutex_init(m, n)                       do { } while (0)
+#define debug_rt_mutex_deadlock(d, a ,l)                do { } while (0)
+#define debug_rt_mutex_print_deadlock(w)                do { } while (0)
+#define debug_rt_mutex_detect_deadlock(w,d)             (d)
+#define debug_rt_mutex_reset_waiter(w)                  do { } while (0)
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
new file mode 100644
index 000000000000..53a66c85261b
--- /dev/null
+++ b/kernel/locking/rtmutex_common.h
@@ -0,0 +1,126 @@
+/*
+ * RT Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains the private data structure and API definitions.
+ */
+
+#ifndef __KERNEL_RTMUTEX_COMMON_H
+#define __KERNEL_RTMUTEX_COMMON_H
+
+#include <linux/rtmutex.h>
+
+/*
+ * The rtmutex in kernel tester is independent of rtmutex debugging. We
+ * call schedule_rt_mutex_test() instead of schedule() for the tasks which
+ * belong to the tester. That way we can delay the wakeup path of those
+ * threads to provoke lock stealing and testing of  complex boosting scenarios.
+ */
+#ifdef CONFIG_RT_MUTEX_TESTER
+
+extern void schedule_rt_mutex_test(struct rt_mutex *lock);
+
+#define schedule_rt_mutex(_lock)                                \
+  do {                                                          \
+        if (!(current->flags & PF_MUTEX_TESTER))                \
+                schedule();                                     \
+        else                                                    \
+                schedule_rt_mutex_test(_lock);                  \
+  } while (0)
+
+#else
+# define schedule_rt_mutex(_lock)                       schedule()
+#endif
+
+/*
+ * This is the control structure for tasks blocked on a rt_mutex,
+ * which is allocated on the kernel stack on of the blocked task.
+ *
+ * @list_entry:         pi node to enqueue into the mutex waiters list
+ * @pi_list_entry:      pi node to enqueue into the mutex owner waiters list
+ * @task:               task reference to the blocked task
+ */
+struct rt_mutex_waiter {
+        struct plist_node       list_entry;
+        struct plist_node       pi_list_entry;
+        struct task_struct      *task;
+        struct rt_mutex         *lock;
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+        unsigned long           ip;
+        struct pid              *deadlock_task_pid;
+        struct rt_mutex         *deadlock_lock;
+#endif
+};
+
+/*
+ * Various helpers to access the waiters-plist:
+ */
+static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
+{
+        return !plist_head_empty(&lock->wait_list);
+}
+
+static inline struct rt_mutex_waiter *
+rt_mutex_top_waiter(struct rt_mutex *lock)
+{
+        struct rt_mutex_waiter *w;
+
+        w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter,
+                               list_entry);
+        BUG_ON(w->lock != lock);
+
+        return w;
+}
+
+static inline int task_has_pi_waiters(struct task_struct *p)
+{
+        return !plist_head_empty(&p->pi_waiters);
+}
+
+static inline struct rt_mutex_waiter *
+task_top_pi_waiter(struct task_struct *p)
+{
+        return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter,
+                                  pi_list_entry);
+}
+
+/*
+ * lock->owner state tracking:
+ */
+#define RT_MUTEX_HAS_WAITERS    1UL
+#define RT_MUTEX_OWNER_MASKALL  1UL
+
+static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
+{
+        return (struct task_struct *)
+                ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
+}
+
+/*
+ * PI-futex support (proxy locking functions, etc.):
+ */
+extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
+extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+                                       struct task_struct *proxy_owner);
+extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
+                                  struct task_struct *proxy_owner);
+extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+                                     struct rt_mutex_waiter *waiter,
+                                     struct task_struct *task,
+                                     int detect_deadlock);
+extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
+                                      struct hrtimer_sleeper *to,
+                                      struct rt_mutex_waiter *waiter,
+                                      int detect_deadlock);
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+# include "rtmutex-debug.h"
+#else
+# include "rtmutex.h"
+#endif
+
+#endif
diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
new file mode 100644
index 000000000000..9be8a9144978
--- /dev/null
+++ b/kernel/locking/rwsem-spinlock.c
@@ -0,0 +1,296 @@
+/* rwsem-spinlock.c: R/W semaphores: contention handling functions for
+ * generic spinlock implementation
+ *
+ * Copyright (c) 2001   David Howells (dhowells@redhat.com).
+ * - Derived partially from idea by Andrea Arcangeli <andrea@suse.de>
+ * - Derived also from comments by Linus
+ */
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/export.h>
+
+enum rwsem_waiter_type {
+        RWSEM_WAITING_FOR_WRITE,
+        RWSEM_WAITING_FOR_READ
+};
+
+struct rwsem_waiter {
+        struct list_head list;
+        struct task_struct *task;
+        enum rwsem_waiter_type type;
+};
+
+int rwsem_is_locked(struct rw_semaphore *sem)
+{
+        int ret = 1;
+        unsigned long flags;
+
+        if (raw_spin_trylock_irqsave(&sem->wait_lock, flags)) {
+                ret = (sem->activity != 0);
+                raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+        }
+        return ret;
+}
+EXPORT_SYMBOL(rwsem_is_locked);
+
+/*
+ * initialise the semaphore
+ */
+void __init_rwsem(struct rw_semaphore *sem, const char *name,
+                  struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /*
+         * Make sure we are not reinitializing a held semaphore:
+         */
+        debug_check_no_locks_freed((void *)sem, sizeof(*sem));
+        lockdep_init_map(&sem->dep_map, name, key, 0);
+#endif
+        sem->activity = 0;
+        raw_spin_lock_init(&sem->wait_lock);
+        INIT_LIST_HEAD(&sem->wait_list);
+}
+EXPORT_SYMBOL(__init_rwsem);
+
+/*
+ * handle the lock release when processes blocked on it that can now run
+ * - if we come here, then:
+ *   - the 'active count' _reached_ zero
+ *   - the 'waiting count' is non-zero
+ * - the spinlock must be held by the caller
+ * - woken process blocks are discarded from the list after having task zeroed
+ * - writers are only woken if wakewrite is non-zero
+ */
+static inline struct rw_semaphore *
+__rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
+{
+        struct rwsem_waiter *waiter;
+        struct task_struct *tsk;
+        int woken;
+
+        waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
+
+        if (waiter->type == RWSEM_WAITING_FOR_WRITE) {
+                if (wakewrite)
+                        /* Wake up a writer. Note that we do not grant it the
+                         * lock - it will have to acquire it when it runs. */
+                        wake_up_process(waiter->task);
+                goto out;
+        }
+
+        /* grant an infinite number of read locks to the front of the queue */
+        woken = 0;
+        do {
+                struct list_head *next = waiter->list.next;
+
+                list_del(&waiter->list);
+                tsk = waiter->task;
+                smp_mb();
+                waiter->task = NULL;
+                wake_up_process(tsk);
+                put_task_struct(tsk);
+                woken++;
+                if (next == &sem->wait_list)
+                        break;
+                waiter = list_entry(next, struct rwsem_waiter, list);
+        } while (waiter->type != RWSEM_WAITING_FOR_WRITE);
+
+        sem->activity += woken;
+
+ out:
+        return sem;
+}
+
+/*
+ * wake a single writer
+ */
+static inline struct rw_semaphore *
+__rwsem_wake_one_writer(struct rw_semaphore *sem)
+{
+        struct rwsem_waiter *waiter;
+
+        waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
+        wake_up_process(waiter->task);
+
+        return sem;
+}
+
+/*
+ * get a read lock on the semaphore
+ */
+void __sched __down_read(struct rw_semaphore *sem)
+{
+        struct rwsem_waiter waiter;
+        struct task_struct *tsk;
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        if (sem->activity >= 0 && list_empty(&sem->wait_list)) {
+                /* granted */
+                sem->activity++;
+                raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+                goto out;
+        }
+
+        tsk = current;
+        set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+
+        /* set up my own style of waitqueue */
+        waiter.task = tsk;
+        waiter.type = RWSEM_WAITING_FOR_READ;
+        get_task_struct(tsk);
+
+        list_add_tail(&waiter.list, &sem->wait_list);
+
+        /* we don't need to touch the semaphore struct anymore */
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+        /* wait to be given the lock */
+        for (;;) {
+                if (!waiter.task)
+                        break;
+                schedule();
+                set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+        }
+
+        tsk->state = TASK_RUNNING;
+ out:
+        ;
+}
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+int __down_read_trylock(struct rw_semaphore *sem)
+{
+        unsigned long flags;
+        int ret = 0;
+
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        if (sem->activity >= 0 && list_empty(&sem->wait_list)) {
+                /* granted */
+                sem->activity++;
+                ret = 1;
+        }
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+        return ret;
+}
+
+/*
+ * get a write lock on the semaphore
+ */
+void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
+{
+        struct rwsem_waiter waiter;
+        struct task_struct *tsk;
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        /* set up my own style of waitqueue */
+        tsk = current;
+        waiter.task = tsk;
+        waiter.type = RWSEM_WAITING_FOR_WRITE;
+        list_add_tail(&waiter.list, &sem->wait_list);
+
+        /* wait for someone to release the lock */
+        for (;;) {
+                /*
+                 * That is the key to support write lock stealing: allows the
+                 * task already on CPU to get the lock soon rather than put
+                 * itself into sleep and waiting for system woke it or someone
+                 * else in the head of the wait list up.
+                 */
+                if (sem->activity == 0)
+                        break;
+                set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+                schedule();
+                raw_spin_lock_irqsave(&sem->wait_lock, flags);
+        }
+        /* got the lock */
+        sem->activity = -1;
+        list_del(&waiter.list);
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
+void __sched __down_write(struct rw_semaphore *sem)
+{
+        __down_write_nested(sem, 0);
+}
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+int __down_write_trylock(struct rw_semaphore *sem)
+{
+        unsigned long flags;
+        int ret = 0;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        if (sem->activity == 0) {
+                /* got the lock */
+                sem->activity = -1;
+                ret = 1;
+        }
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+        return ret;
+}
+
+/*
+ * release a read lock on the semaphore
+ */
+void __up_read(struct rw_semaphore *sem)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        if (--sem->activity == 0 && !list_empty(&sem->wait_list))
+                sem = __rwsem_wake_one_writer(sem);
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
+/*
+ * release a write lock on the semaphore
+ */
+void __up_write(struct rw_semaphore *sem)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        sem->activity = 0;
+        if (!list_empty(&sem->wait_list))
+                sem = __rwsem_do_wake(sem, 1);
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
+/*
+ * downgrade a write lock into a read lock
+ * - just wake up any readers at the front of the queue
+ */
+void __downgrade_write(struct rw_semaphore *sem)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        sem->activity = 1;
+        if (!list_empty(&sem->wait_list))
+                sem = __rwsem_do_wake(sem, 0);
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+}
+
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
new file mode 100644
index 000000000000..19c5fa95e0b4
--- /dev/null
+++ b/kernel/locking/rwsem-xadd.c
@@ -0,0 +1,293 @@
+/* rwsem.c: R/W semaphores: contention handling functions
+ *
+ * Written by David Howells (dhowells@redhat.com).
+ * Derived from arch/i386/kernel/semaphore.c
+ *
+ * Writer lock-stealing by Alex Shi <alex.shi@intel.com>
+ * and Michel Lespinasse <walken@google.com>
+ */
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/export.h>
+
+/*
+ * Initialize an rwsem:
+ */
+void __init_rwsem(struct rw_semaphore *sem, const char *name,
+                  struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /*
+         * Make sure we are not reinitializing a held semaphore:
+         */
+        debug_check_no_locks_freed((void *)sem, sizeof(*sem));
+        lockdep_init_map(&sem->dep_map, name, key, 0);
+#endif
+        sem->count = RWSEM_UNLOCKED_VALUE;
+        raw_spin_lock_init(&sem->wait_lock);
+        INIT_LIST_HEAD(&sem->wait_list);
+}
+
+EXPORT_SYMBOL(__init_rwsem);
+
+enum rwsem_waiter_type {
+        RWSEM_WAITING_FOR_WRITE,
+        RWSEM_WAITING_FOR_READ
+};
+
+struct rwsem_waiter {
+        struct list_head list;
+        struct task_struct *task;
+        enum rwsem_waiter_type type;
+};
+
+enum rwsem_wake_type {
+        RWSEM_WAKE_ANY,         /* Wake whatever's at head of wait list */
+        RWSEM_WAKE_READERS,     /* Wake readers only */
+        RWSEM_WAKE_READ_OWNED   /* Waker thread holds the read lock */
+};
+
+/*
+ * handle the lock release when processes blocked on it that can now run
+ * - if we come here from up_xxxx(), then:
+ *   - the 'active part' of count (&0x0000ffff) reached 0 (but may have changed)
+ *   - the 'waiting part' of count (&0xffff0000) is -ve (and will still be so)
+ * - there must be someone on the queue
+ * - the spinlock must be held by the caller
+ * - woken process blocks are discarded from the list after having task zeroed
+ * - writers are only woken if downgrading is false
+ */
+static struct rw_semaphore *
+__rwsem_do_wake(struct rw_semaphore *sem, enum rwsem_wake_type wake_type)
+{
+        struct rwsem_waiter *waiter;
+        struct task_struct *tsk;
+        struct list_head *next;
+        long oldcount, woken, loop, adjustment;
+
+        waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
+        if (waiter->type == RWSEM_WAITING_FOR_WRITE) {
+                if (wake_type == RWSEM_WAKE_ANY)
+                        /* Wake writer at the front of the queue, but do not
+                         * grant it the lock yet as we want other writers
+                         * to be able to steal it.  Readers, on the other hand,
+                         * will block as they will notice the queued writer.
+                         */
+                        wake_up_process(waiter->task);
+                goto out;
+        }
+
+        /* Writers might steal the lock before we grant it to the next reader.
+         * We prefer to do the first reader grant before counting readers
+         * so we can bail out early if a writer stole the lock.
+         */
+        adjustment = 0;
+        if (wake_type != RWSEM_WAKE_READ_OWNED) {
+                adjustment = RWSEM_ACTIVE_READ_BIAS;
+ try_reader_grant:
+                oldcount = rwsem_atomic_update(adjustment, sem) - adjustment;
+                if (unlikely(oldcount < RWSEM_WAITING_BIAS)) {
+                        /* A writer stole the lock. Undo our reader grant. */
+                        if (rwsem_atomic_update(-adjustment, sem) &
+                                                RWSEM_ACTIVE_MASK)
+                                goto out;
+                        /* Last active locker left. Retry waking readers. */
+                        goto try_reader_grant;
+                }
+        }
+
+        /* Grant an infinite number of read locks to the readers at the front
+         * of the queue.  Note we increment the 'active part' of the count by
+         * the number of readers before waking any processes up.
+         */
+        woken = 0;
+        do {
+                woken++;
+
+                if (waiter->list.next == &sem->wait_list)
+                        break;
+
+                waiter = list_entry(waiter->list.next,
+                                        struct rwsem_waiter, list);
+
+        } while (waiter->type != RWSEM_WAITING_FOR_WRITE);
+
+        adjustment = woken * RWSEM_ACTIVE_READ_BIAS - adjustment;
+        if (waiter->type != RWSEM_WAITING_FOR_WRITE)
+                /* hit end of list above */
+                adjustment -= RWSEM_WAITING_BIAS;
+
+        if (adjustment)
+                rwsem_atomic_add(adjustment, sem);
+
+        next = sem->wait_list.next;
+        loop = woken;
+        do {
+                waiter = list_entry(next, struct rwsem_waiter, list);
+                next = waiter->list.next;
+                tsk = waiter->task;
+                smp_mb();
+                waiter->task = NULL;
+                wake_up_process(tsk);
+                put_task_struct(tsk);
+        } while (--loop);
+
+        sem->wait_list.next = next;
+        next->prev = &sem->wait_list;
+
+ out:
+        return sem;
+}
+
+/*
+ * wait for the read lock to be granted
+ */
+struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
+{
+        long count, adjustment = -RWSEM_ACTIVE_READ_BIAS;
+        struct rwsem_waiter waiter;
+        struct task_struct *tsk = current;
+
+        /* set up my own style of waitqueue */
+        waiter.task = tsk;
+        waiter.type = RWSEM_WAITING_FOR_READ;
+        get_task_struct(tsk);
+
+        raw_spin_lock_irq(&sem->wait_lock);
+        if (list_empty(&sem->wait_list))
+                adjustment += RWSEM_WAITING_BIAS;
+        list_add_tail(&waiter.list, &sem->wait_list);
+
+        /* we're now waiting on the lock, but no longer actively locking */
+        count = rwsem_atomic_update(adjustment, sem);
+
+        /* If there are no active locks, wake the front queued process(es).
+         *
+         * If there are no writers and we are first in the queue,
+         * wake our own waiter to join the existing active readers !
+         */
+        if (count == RWSEM_WAITING_BIAS ||
+            (count > RWSEM_WAITING_BIAS &&
+             adjustment != -RWSEM_ACTIVE_READ_BIAS))
+                sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
+
+        raw_spin_unlock_irq(&sem->wait_lock);
+
+        /* wait to be given the lock */
+        while (true) {
+                set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                if (!waiter.task)
+                        break;
+                schedule();
+        }
+
+        tsk->state = TASK_RUNNING;
+
+        return sem;
+}
+
+/*
+ * wait until we successfully acquire the write lock
+ */
+struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
+{
+        long count, adjustment = -RWSEM_ACTIVE_WRITE_BIAS;
+        struct rwsem_waiter waiter;
+        struct task_struct *tsk = current;
+
+        /* set up my own style of waitqueue */
+        waiter.task = tsk;
+        waiter.type = RWSEM_WAITING_FOR_WRITE;
+
+        raw_spin_lock_irq(&sem->wait_lock);
+        if (list_empty(&sem->wait_list))
+                adjustment += RWSEM_WAITING_BIAS;
+        list_add_tail(&waiter.list, &sem->wait_list);
+
+        /* we're now waiting on the lock, but no longer actively locking */
+        count = rwsem_atomic_update(adjustment, sem);
+
+        /* If there were already threads queued before us and there are no
+         * active writers, the lock must be read owned; so we try to wake
+         * any read locks that were queued ahead of us. */
+        if (count > RWSEM_WAITING_BIAS &&
+            adjustment == -RWSEM_ACTIVE_WRITE_BIAS)
+                sem = __rwsem_do_wake(sem, RWSEM_WAKE_READERS);
+
+        /* wait until we successfully acquire the lock */
+        set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+        while (true) {
+                if (!(count & RWSEM_ACTIVE_MASK)) {
+                        /* Try acquiring the write lock. */
+                        count = RWSEM_ACTIVE_WRITE_BIAS;
+                        if (!list_is_singular(&sem->wait_list))
+                                count += RWSEM_WAITING_BIAS;
+
+                        if (sem->count == RWSEM_WAITING_BIAS &&
+                            cmpxchg(&sem->count, RWSEM_WAITING_BIAS, count) ==
+                                                        RWSEM_WAITING_BIAS)
+                                break;
+                }
+
+                raw_spin_unlock_irq(&sem->wait_lock);
+
+                /* Block until there are no active lockers. */
+                do {
+                        schedule();
+                        set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                } while ((count = sem->count) & RWSEM_ACTIVE_MASK);
+
+                raw_spin_lock_irq(&sem->wait_lock);
+        }
+
+        list_del(&waiter.list);
+        raw_spin_unlock_irq(&sem->wait_lock);
+        tsk->state = TASK_RUNNING;
+
+        return sem;
+}
+
+/*
+ * handle waking up a waiter on the semaphore
+ * - up_read/up_write has decremented the active part of count if we come here
+ */
+struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        /* do nothing if list empty */
+        if (!list_empty(&sem->wait_list))
+                sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+        return sem;
+}
+
+/*
+ * downgrade a write lock into a read lock
+ * - caller incremented waiting part of count and discovered it still negative
+ * - just wake up any readers at the front of the queue
+ */
+struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->wait_lock, flags);
+
+        /* do nothing if list empty */
+        if (!list_empty(&sem->wait_list))
+                sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
+
+        raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+        return sem;
+}
+
+EXPORT_SYMBOL(rwsem_down_read_failed);
+EXPORT_SYMBOL(rwsem_down_write_failed);
+EXPORT_SYMBOL(rwsem_wake);
+EXPORT_SYMBOL(rwsem_downgrade_wake);
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
new file mode 100644
index 000000000000..cfff1435bdfb
--- /dev/null
+++ b/kernel/locking/rwsem.c
@@ -0,0 +1,157 @@
+/* kernel/rwsem.c: R/W semaphores, public implementation
+ *
+ * Written by David Howells (dhowells@redhat.com).
+ * Derived from asm-i386/semaphore.h
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/export.h>
+#include <linux/rwsem.h>
+
+#include <linux/atomic.h>
+
+/*
+ * lock for reading
+ */
+void __sched down_read(struct rw_semaphore *sem)
+{
+        might_sleep();
+        rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
+
+        LOCK_CONTENDED(sem, __down_read_trylock, __down_read);
+}
+
+EXPORT_SYMBOL(down_read);
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+int down_read_trylock(struct rw_semaphore *sem)
+{
+        int ret = __down_read_trylock(sem);
+
+        if (ret == 1)
+                rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
+        return ret;
+}
+
+EXPORT_SYMBOL(down_read_trylock);
+
+/*
+ * lock for writing
+ */
+void __sched down_write(struct rw_semaphore *sem)
+{
+        might_sleep();
+        rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+
+        LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
+}
+
+EXPORT_SYMBOL(down_write);
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+int down_write_trylock(struct rw_semaphore *sem)
+{
+        int ret = __down_write_trylock(sem);
+
+        if (ret == 1)
+                rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_);
+        return ret;
+}
+
+EXPORT_SYMBOL(down_write_trylock);
+
+/*
+ * release a read lock
+ */
+void up_read(struct rw_semaphore *sem)
+{
+        rwsem_release(&sem->dep_map, 1, _RET_IP_);
+
+        __up_read(sem);
+}
+
+EXPORT_SYMBOL(up_read);
+
+/*
+ * release a write lock
+ */
+void up_write(struct rw_semaphore *sem)
+{
+        rwsem_release(&sem->dep_map, 1, _RET_IP_);
+
+        __up_write(sem);
+}
+
+EXPORT_SYMBOL(up_write);
+
+/*
+ * downgrade write lock to read lock
+ */
+void downgrade_write(struct rw_semaphore *sem)
+{
+        /*
+         * lockdep: a downgraded write will live on as a write
+         * dependency.
+         */
+        __downgrade_write(sem);
+}
+
+EXPORT_SYMBOL(downgrade_write);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+void down_read_nested(struct rw_semaphore *sem, int subclass)
+{
+        might_sleep();
+        rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_);
+
+        LOCK_CONTENDED(sem, __down_read_trylock, __down_read);
+}
+
+EXPORT_SYMBOL(down_read_nested);
+
+void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)
+{
+        might_sleep();
+        rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_);
+
+        LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
+}
+
+EXPORT_SYMBOL(_down_write_nest_lock);
+
+void down_read_non_owner(struct rw_semaphore *sem)
+{
+        might_sleep();
+
+        __down_read(sem);
+}
+
+EXPORT_SYMBOL(down_read_non_owner);
+
+void down_write_nested(struct rw_semaphore *sem, int subclass)
+{
+        might_sleep();
+        rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_);
+
+        LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
+}
+
+EXPORT_SYMBOL(down_write_nested);
+
+void up_read_non_owner(struct rw_semaphore *sem)
+{
+        __up_read(sem);
+}
+
+EXPORT_SYMBOL(up_read_non_owner);
+
+#endif
+
+
diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
new file mode 100644
index 000000000000..6815171a4fff
--- /dev/null
+++ b/kernel/locking/semaphore.c
@@ -0,0 +1,263 @@
+/*
+ * Copyright (c) 2008 Intel Corporation
+ * Author: Matthew Wilcox <willy@linux.intel.com>
+ *
+ * Distributed under the terms of the GNU GPL, version 2
+ *
+ * This file implements counting semaphores.
+ * A counting semaphore may be acquired 'n' times before sleeping.
+ * See mutex.c for single-acquisition sleeping locks which enforce
+ * rules which allow code to be debugged more easily.
+ */
+
+/*
+ * Some notes on the implementation:
+ *
+ * The spinlock controls access to the other members of the semaphore.
+ * down_trylock() and up() can be called from interrupt context, so we
+ * have to disable interrupts when taking the lock.  It turns out various
+ * parts of the kernel expect to be able to use down() on a semaphore in
+ * interrupt context when they know it will succeed, so we have to use
+ * irqsave variants for down(), down_interruptible() and down_killable()
+ * too.
+ *
+ * The ->count variable represents how many more tasks can acquire this
+ * semaphore.  If it's zero, there may be tasks waiting on the wait_list.
+ */
+
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/semaphore.h>
+#include <linux/spinlock.h>
+#include <linux/ftrace.h>
+
+static noinline void __down(struct semaphore *sem);
+static noinline int __down_interruptible(struct semaphore *sem);
+static noinline int __down_killable(struct semaphore *sem);
+static noinline int __down_timeout(struct semaphore *sem, long jiffies);
+static noinline void __up(struct semaphore *sem);
+
+/**
+ * down - acquire the semaphore
+ * @sem: the semaphore to be acquired
+ *
+ * Acquires the semaphore.  If no more tasks are allowed to acquire the
+ * semaphore, calling this function will put the task to sleep until the
+ * semaphore is released.
+ *
+ * Use of this function is deprecated, please use down_interruptible() or
+ * down_killable() instead.
+ */
+void down(struct semaphore *sem)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->lock, flags);
+        if (likely(sem->count > 0))
+                sem->count--;
+        else
+                __down(sem);
+        raw_spin_unlock_irqrestore(&sem->lock, flags);
+}
+EXPORT_SYMBOL(down);
+
+/**
+ * down_interruptible - acquire the semaphore unless interrupted
+ * @sem: the semaphore to be acquired
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the sleep is interrupted by a signal, this function will return -EINTR.
+ * If the semaphore is successfully acquired, this function returns 0.
+ */
+int down_interruptible(struct semaphore *sem)
+{
+        unsigned long flags;
+        int result = 0;
+
+        raw_spin_lock_irqsave(&sem->lock, flags);
+        if (likely(sem->count > 0))
+                sem->count--;
+        else
+                result = __down_interruptible(sem);
+        raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+        return result;
+}
+EXPORT_SYMBOL(down_interruptible);
+
+/**
+ * down_killable - acquire the semaphore unless killed
+ * @sem: the semaphore to be acquired
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the sleep is interrupted by a fatal signal, this function will return
+ * -EINTR.  If the semaphore is successfully acquired, this function returns
+ * 0.
+ */
+int down_killable(struct semaphore *sem)
+{
+        unsigned long flags;
+        int result = 0;
+
+        raw_spin_lock_irqsave(&sem->lock, flags);
+        if (likely(sem->count > 0))
+                sem->count--;
+        else
+                result = __down_killable(sem);
+        raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+        return result;
+}
+EXPORT_SYMBOL(down_killable);
+
+/**
+ * down_trylock - try to acquire the semaphore, without waiting
+ * @sem: the semaphore to be acquired
+ *
+ * Try to acquire the semaphore atomically.  Returns 0 if the semaphore has
+ * been acquired successfully or 1 if it it cannot be acquired.
+ *
+ * NOTE: This return value is inverted from both spin_trylock and
+ * mutex_trylock!  Be careful about this when converting code.
+ *
+ * Unlike mutex_trylock, this function can be used from interrupt context,
+ * and the semaphore can be released by any task or interrupt.
+ */
+int down_trylock(struct semaphore *sem)
+{
+        unsigned long flags;
+        int count;
+
+        raw_spin_lock_irqsave(&sem->lock, flags);
+        count = sem->count - 1;
+        if (likely(count >= 0))
+                sem->count = count;
+        raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+        return (count < 0);
+}
+EXPORT_SYMBOL(down_trylock);
+
+/**
+ * down_timeout - acquire the semaphore within a specified time
+ * @sem: the semaphore to be acquired
+ * @jiffies: how long to wait before failing
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the semaphore is not released within the specified number of jiffies,
+ * this function returns -ETIME.  It returns 0 if the semaphore was acquired.
+ */
+int down_timeout(struct semaphore *sem, long jiffies)
+{
+        unsigned long flags;
+        int result = 0;
+
+        raw_spin_lock_irqsave(&sem->lock, flags);
+        if (likely(sem->count > 0))
+                sem->count--;
+        else
+                result = __down_timeout(sem, jiffies);
+        raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+        return result;
+}
+EXPORT_SYMBOL(down_timeout);
+
+/**
+ * up - release the semaphore
+ * @sem: the semaphore to release
+ *
+ * Release the semaphore.  Unlike mutexes, up() may be called from any
+ * context and even by tasks which have never called down().
+ */
+void up(struct semaphore *sem)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&sem->lock, flags);
+        if (likely(list_empty(&sem->wait_list)))
+                sem->count++;
+        else
+                __up(sem);
+        raw_spin_unlock_irqrestore(&sem->lock, flags);
+}
+EXPORT_SYMBOL(up);
+
+/* Functions for the contended case */
+
+struct semaphore_waiter {
+        struct list_head list;
+        struct task_struct *task;
+        bool up;
+};
+
+/*
+ * Because this function is inlined, the 'state' parameter will be
+ * constant, and thus optimised away by the compiler.  Likewise the
+ * 'timeout' parameter for the cases without timeouts.
+ */
+static inline int __sched __down_common(struct semaphore *sem, long state,
+                                                                long timeout)
+{
+        struct task_struct *task = current;
+        struct semaphore_waiter waiter;
+
+        list_add_tail(&waiter.list, &sem->wait_list);
+        waiter.task = task;
+        waiter.up = false;
+
+        for (;;) {
+                if (signal_pending_state(state, task))
+                        goto interrupted;
+                if (unlikely(timeout <= 0))
+                        goto timed_out;
+                __set_task_state(task, state);
+                raw_spin_unlock_irq(&sem->lock);
+                timeout = schedule_timeout(timeout);
+                raw_spin_lock_irq(&sem->lock);
+                if (waiter.up)
+                        return 0;
+        }
+
+ timed_out:
+        list_del(&waiter.list);
+        return -ETIME;
+
+ interrupted:
+        list_del(&waiter.list);
+        return -EINTR;
+}
+
+static noinline void __sched __down(struct semaphore *sem)
+{
+        __down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_interruptible(struct semaphore *sem)
+{
+        return __down_common(sem, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_killable(struct semaphore *sem)
+{
+        return __down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_timeout(struct semaphore *sem, long jiffies)
+{
+        return __down_common(sem, TASK_UNINTERRUPTIBLE, jiffies);
+}
+
+static noinline void __sched __up(struct semaphore *sem)
+{
+        struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list,
+                                                struct semaphore_waiter, list);
+        list_del(&waiter->list);
+        waiter->up = true;
+        wake_up_process(waiter->task);
+}
diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c
new file mode 100644
index 000000000000..4b082b5cac9e
--- /dev/null
+++ b/kernel/locking/spinlock.c
@@ -0,0 +1,399 @@
+/*
+ * Copyright (2004) Linus Torvalds
+ *
+ * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
+ *
+ * Copyright (2004, 2005) Ingo Molnar
+ *
+ * This file contains the spinlock/rwlock implementations for the
+ * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
+ *
+ * Note that some architectures have special knowledge about the
+ * stack frames of these functions in their profile_pc. If you
+ * change anything significant here that could change the stack
+ * frame contact the architecture maintainers.
+ */
+
+#include <linux/linkage.h>
+#include <linux/preempt.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+#include <linux/export.h>
+
+/*
+ * If lockdep is enabled then we use the non-preemption spin-ops
+ * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
+ * not re-enabled during lock-acquire (which the preempt-spin-ops do):
+ */
+#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
+/*
+ * The __lock_function inlines are taken from
+ * include/linux/spinlock_api_smp.h
+ */
+#else
+#define raw_read_can_lock(l)    read_can_lock(l)
+#define raw_write_can_lock(l)   write_can_lock(l)
+
+/*
+ * Some architectures can relax in favour of the CPU owning the lock.
+ */
+#ifndef arch_read_relax
+# define arch_read_relax(l)     cpu_relax()
+#endif
+#ifndef arch_write_relax
+# define arch_write_relax(l)    cpu_relax()
+#endif
+#ifndef arch_spin_relax
+# define arch_spin_relax(l)     cpu_relax()
+#endif
+
+/*
+ * We build the __lock_function inlines here. They are too large for
+ * inlining all over the place, but here is only one user per function
+ * which embedds them into the calling _lock_function below.
+ *
+ * This could be a long-held lock. We both prepare to spin for a long
+ * time (making _this_ CPU preemptable if possible), and we also signal
+ * towards that other CPU that it should break the lock ASAP.
+ */
+#define BUILD_LOCK_OPS(op, locktype)                                    \
+void __lockfunc __raw_##op##_lock(locktype##_t *lock)                   \
+{                                                                       \
+        for (;;) {                                                      \
+                preempt_disable();                                      \
+                if (likely(do_raw_##op##_trylock(lock)))                \
+                        break;                                          \
+                preempt_enable();                                       \
+                                                                        \
+                if (!(lock)->break_lock)                                \
+                        (lock)->break_lock = 1;                         \
+                while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
+                        arch_##op##_relax(&lock->raw_lock);             \
+        }                                                               \
+        (lock)->break_lock = 0;                                         \
+}                                                                       \
+                                                                        \
+unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock)  \
+{                                                                       \
+        unsigned long flags;                                            \
+                                                                        \
+        for (;;) {                                                      \
+                preempt_disable();                                      \
+                local_irq_save(flags);                                  \
+                if (likely(do_raw_##op##_trylock(lock)))                \
+                        break;                                          \
+                local_irq_restore(flags);                               \
+                preempt_enable();                                       \
+                                                                        \
+                if (!(lock)->break_lock)                                \
+                        (lock)->break_lock = 1;                         \
+                while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
+                        arch_##op##_relax(&lock->raw_lock);             \
+        }                                                               \
+        (lock)->break_lock = 0;                                         \
+        return flags;                                                   \
+}                                                                       \
+                                                                        \
+void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)               \
+{                                                                       \
+        _raw_##op##_lock_irqsave(lock);                                 \
+}                                                                       \
+                                                                        \
+void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock)                \
+{                                                                       \
+        unsigned long flags;                                            \
+                                                                        \
+        /*                                                      */      \
+        /* Careful: we must exclude softirqs too, hence the     */      \
+        /* irq-disabling. We use the generic preemption-aware   */      \
+        /* function:                                            */      \
+        /**/                                                            \
+        flags = _raw_##op##_lock_irqsave(lock);                         \
+        local_bh_disable();                                             \
+        local_irq_restore(flags);                                       \
+}                                                                       \
+
+/*
+ * Build preemption-friendly versions of the following
+ * lock-spinning functions:
+ *
+ *         __[spin|read|write]_lock()
+ *         __[spin|read|write]_lock_irq()
+ *         __[spin|read|write]_lock_irqsave()
+ *         __[spin|read|write]_lock_bh()
+ */
+BUILD_LOCK_OPS(spin, raw_spinlock);
+BUILD_LOCK_OPS(read, rwlock);
+BUILD_LOCK_OPS(write, rwlock);
+
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_TRYLOCK
+int __lockfunc _raw_spin_trylock(raw_spinlock_t *lock)
+{
+        return __raw_spin_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
+int __lockfunc _raw_spin_trylock_bh(raw_spinlock_t *lock)
+{
+        return __raw_spin_trylock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_trylock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK
+void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)
+{
+        __raw_spin_lock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_spin_lock_irqsave(raw_spinlock_t *lock)
+{
+        return __raw_spin_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
+void __lockfunc _raw_spin_lock_irq(raw_spinlock_t *lock)
+{
+        __raw_spin_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_BH
+void __lockfunc _raw_spin_lock_bh(raw_spinlock_t *lock)
+{
+        __raw_spin_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_bh);
+#endif
+
+#ifdef CONFIG_UNINLINE_SPIN_UNLOCK
+void __lockfunc _raw_spin_unlock(raw_spinlock_t *lock)
+{
+        __raw_spin_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
+void __lockfunc _raw_spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
+{
+        __raw_spin_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
+void __lockfunc _raw_spin_unlock_irq(raw_spinlock_t *lock)
+{
+        __raw_spin_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
+void __lockfunc _raw_spin_unlock_bh(raw_spinlock_t *lock)
+{
+        __raw_spin_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_READ_TRYLOCK
+int __lockfunc _raw_read_trylock(rwlock_t *lock)
+{
+        return __raw_read_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_read_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK
+void __lockfunc _raw_read_lock(rwlock_t *lock)
+{
+        __raw_read_lock(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
+{
+        return __raw_read_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_IRQ
+void __lockfunc _raw_read_lock_irq(rwlock_t *lock)
+{
+        __raw_read_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_BH
+void __lockfunc _raw_read_lock_bh(rwlock_t *lock)
+{
+        __raw_read_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK
+void __lockfunc _raw_read_unlock(rwlock_t *lock)
+{
+        __raw_read_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
+void __lockfunc _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+{
+        __raw_read_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_read_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
+void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)
+{
+        __raw_read_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_BH
+void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)
+{
+        __raw_read_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_TRYLOCK
+int __lockfunc _raw_write_trylock(rwlock_t *lock)
+{
+        return __raw_write_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_write_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK
+void __lockfunc _raw_write_lock(rwlock_t *lock)
+{
+        __raw_write_lock(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
+{
+        return __raw_write_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
+void __lockfunc _raw_write_lock_irq(rwlock_t *lock)
+{
+        __raw_write_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_BH
+void __lockfunc _raw_write_lock_bh(rwlock_t *lock)
+{
+        __raw_write_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK
+void __lockfunc _raw_write_unlock(rwlock_t *lock)
+{
+        __raw_write_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
+void __lockfunc _raw_write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+{
+        __raw_write_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_write_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
+void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)
+{
+        __raw_write_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
+void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)
+{
+        __raw_write_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock_bh);
+#endif
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
+{
+        preempt_disable();
+        spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+        LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_nested);
+
+unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
+                                                   int subclass)
+{
+        unsigned long flags;
+
+        local_irq_save(flags);
+        preempt_disable();
+        spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+        LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
+                                do_raw_spin_lock_flags, &flags);
+        return flags;
+}
+EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);
+
+void __lockfunc _raw_spin_lock_nest_lock(raw_spinlock_t *lock,
+                                     struct lockdep_map *nest_lock)
+{
+        preempt_disable();
+        spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
+        LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_nest_lock);
+
+#endif
+
+notrace int in_lock_functions(unsigned long addr)
+{
+        /* Linker adds these: start and end of __lockfunc functions */
+        extern char __lock_text_start[], __lock_text_end[];
+
+        return addr >= (unsigned long)__lock_text_start
+        && addr < (unsigned long)__lock_text_end;
+}
+EXPORT_SYMBOL(in_lock_functions);
diff --git a/kernel/locking/spinlock_debug.c b/kernel/locking/spinlock_debug.c
new file mode 100644
index 000000000000..0374a596cffa
--- /dev/null
+++ b/kernel/locking/spinlock_debug.c
@@ -0,0 +1,302 @@
+/*
+ * Copyright 2005, Red Hat, Inc., Ingo Molnar
+ * Released under the General Public License (GPL).
+ *
+ * This file contains the spinlock/rwlock implementations for
+ * DEBUG_SPINLOCK.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/nmi.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+
+void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
+                          struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /*
+         * Make sure we are not reinitializing a held lock:
+         */
+        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+        lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+        lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+        lock->magic = SPINLOCK_MAGIC;
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+EXPORT_SYMBOL(__raw_spin_lock_init);
+
+void __rwlock_init(rwlock_t *lock, const char *name,
+                   struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /*
+         * Make sure we are not reinitializing a held lock:
+         */
+        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+        lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+        lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
+        lock->magic = RWLOCK_MAGIC;
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+EXPORT_SYMBOL(__rwlock_init);
+
+static void spin_dump(raw_spinlock_t *lock, const char *msg)
+{
+        struct task_struct *owner = NULL;
+
+        if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
+                owner = lock->owner;
+        printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
+                msg, raw_smp_processor_id(),
+                current->comm, task_pid_nr(current));
+        printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
+                        ".owner_cpu: %d\n",
+                lock, lock->magic,
+                owner ? owner->comm : "<none>",
+                owner ? task_pid_nr(owner) : -1,
+                lock->owner_cpu);
+        dump_stack();
+}
+
+static void spin_bug(raw_spinlock_t *lock, const char *msg)
+{
+        if (!debug_locks_off())
+                return;
+
+        spin_dump(lock, msg);
+}
+
+#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
+
+static inline void
+debug_spin_lock_before(raw_spinlock_t *lock)
+{
+        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+        SPIN_BUG_ON(lock->owner == current, lock, "recursion");
+        SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+                                                        lock, "cpu recursion");
+}
+
+static inline void debug_spin_lock_after(raw_spinlock_t *lock)
+{
+        lock->owner_cpu = raw_smp_processor_id();
+        lock->owner = current;
+}
+
+static inline void debug_spin_unlock(raw_spinlock_t *lock)
+{
+        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+        SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
+        SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
+        SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+                                                        lock, "wrong CPU");
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+static void __spin_lock_debug(raw_spinlock_t *lock)
+{
+        u64 i;
+        u64 loops = loops_per_jiffy * HZ;
+
+        for (i = 0; i < loops; i++) {
+                if (arch_spin_trylock(&lock->raw_lock))
+                        return;
+                __delay(1);
+        }
+        /* lockup suspected: */
+        spin_dump(lock, "lockup suspected");
+#ifdef CONFIG_SMP
+        trigger_all_cpu_backtrace();
+#endif
+
+        /*
+         * The trylock above was causing a livelock.  Give the lower level arch
+         * specific lock code a chance to acquire the lock. We have already
+         * printed a warning/backtrace at this point. The non-debug arch
+         * specific code might actually succeed in acquiring the lock.  If it is
+         * not successful, the end-result is the same - there is no forward
+         * progress.
+         */
+        arch_spin_lock(&lock->raw_lock);
+}
+
+void do_raw_spin_lock(raw_spinlock_t *lock)
+{
+        debug_spin_lock_before(lock);
+        if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
+                __spin_lock_debug(lock);
+        debug_spin_lock_after(lock);
+}
+
+int do_raw_spin_trylock(raw_spinlock_t *lock)
+{
+        int ret = arch_spin_trylock(&lock->raw_lock);
+
+        if (ret)
+                debug_spin_lock_after(lock);
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void do_raw_spin_unlock(raw_spinlock_t *lock)
+{
+        debug_spin_unlock(lock);
+        arch_spin_unlock(&lock->raw_lock);
+}
+
+static void rwlock_bug(rwlock_t *lock, const char *msg)
+{
+        if (!debug_locks_off())
+                return;
+
+        printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
+                msg, raw_smp_processor_id(), current->comm,
+                task_pid_nr(current), lock);
+        dump_stack();
+}
+
+#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
+
+#if 0           /* __write_lock_debug() can lock up - maybe this can too? */
+static void __read_lock_debug(rwlock_t *lock)
+{
+        u64 i;
+        u64 loops = loops_per_jiffy * HZ;
+        int print_once = 1;
+
+        for (;;) {
+                for (i = 0; i < loops; i++) {
+                        if (arch_read_trylock(&lock->raw_lock))
+                                return;
+                        __delay(1);
+                }
+                /* lockup suspected: */
+                if (print_once) {
+                        print_once = 0;
+                        printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
+                                        "%s/%d, %p\n",
+                                raw_smp_processor_id(), current->comm,
+                                current->pid, lock);
+                        dump_stack();
+                }
+        }
+}
+#endif
+
+void do_raw_read_lock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        arch_read_lock(&lock->raw_lock);
+}
+
+int do_raw_read_trylock(rwlock_t *lock)
+{
+        int ret = arch_read_trylock(&lock->raw_lock);
+
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void do_raw_read_unlock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        arch_read_unlock(&lock->raw_lock);
+}
+
+static inline void debug_write_lock_before(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
+        RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+                                                        lock, "cpu recursion");
+}
+
+static inline void debug_write_lock_after(rwlock_t *lock)
+{
+        lock->owner_cpu = raw_smp_processor_id();
+        lock->owner = current;
+}
+
+static inline void debug_write_unlock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
+        RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+                                                        lock, "wrong CPU");
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+#if 0           /* This can cause lockups */
+static void __write_lock_debug(rwlock_t *lock)
+{
+        u64 i;
+        u64 loops = loops_per_jiffy * HZ;
+        int print_once = 1;
+
+        for (;;) {
+                for (i = 0; i < loops; i++) {
+                        if (arch_write_trylock(&lock->raw_lock))
+                                return;
+                        __delay(1);
+                }
+                /* lockup suspected: */
+                if (print_once) {
+                        print_once = 0;
+                        printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
+                                        "%s/%d, %p\n",
+                                raw_smp_processor_id(), current->comm,
+                                current->pid, lock);
+                        dump_stack();
+                }
+        }
+}
+#endif
+
+void do_raw_write_lock(rwlock_t *lock)
+{
+        debug_write_lock_before(lock);
+        arch_write_lock(&lock->raw_lock);
+        debug_write_lock_after(lock);
+}
+
+int do_raw_write_trylock(rwlock_t *lock)
+{
+        int ret = arch_write_trylock(&lock->raw_lock);
+
+        if (ret)
+                debug_write_lock_after(lock);
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void do_raw_write_unlock(rwlock_t *lock)
+{
+        debug_write_unlock(lock);
+        arch_write_unlock(&lock->raw_lock);
+}