locking: Move the lockdep code to kernel/locking/

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-wl7s3tta5isufzfguc23et06@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

5 files changed, 5125 insertions, 0 deletions

diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index fe8bd58b22f8..c103599fc1ba 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -2,8 +2,14 @@
 obj-y += mutex.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
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
new file mode 100644
index 000000000000..4e8e14c34e42
--- /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;
+}
+
+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;
+}
+
+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..09220656d888
--- /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 ? do_div(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)