locking: Move the spinlock 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-b81ol0z3mon45m51o131yc9j@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 705 insertions, 0 deletions

diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index c103599fc1ba..674d2152d10f 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -13,3 +13,7 @@ obj-$(CONFIG_LOCKDEP) += lockdep.o
 ifeq ($(CONFIG_PROC_FS),y)
 obj-$(CONFIG_LOCKDEP) += lockdep_proc.o
 endif
+obj-$(CONFIG_SMP) += spinlock.o
+obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c
new file mode 100644
index 000000000000..4b082b5cac9e
--- /dev/null
+++ b/kernel/locking/spinlock.c
@@ -0,0 +1,399 @@
+/*
+ * Copyright (2004) Linus Torvalds
+ *
+ * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
+ *
+ * Copyright (2004, 2005) Ingo Molnar
+ *
+ * This file contains the spinlock/rwlock implementations for the
+ * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
+ *
+ * Note that some architectures have special knowledge about the
+ * stack frames of these functions in their profile_pc. If you
+ * change anything significant here that could change the stack
+ * frame contact the architecture maintainers.
+ */
+
+#include <linux/linkage.h>
+#include <linux/preempt.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+#include <linux/export.h>
+
+/*
+ * If lockdep is enabled then we use the non-preemption spin-ops
+ * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
+ * not re-enabled during lock-acquire (which the preempt-spin-ops do):
+ */
+#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
+/*
+ * The __lock_function inlines are taken from
+ * include/linux/spinlock_api_smp.h
+ */
+#else
+#define raw_read_can_lock(l)    read_can_lock(l)
+#define raw_write_can_lock(l)   write_can_lock(l)
+
+/*
+ * Some architectures can relax in favour of the CPU owning the lock.
+ */
+#ifndef arch_read_relax
+# define arch_read_relax(l)     cpu_relax()
+#endif
+#ifndef arch_write_relax
+# define arch_write_relax(l)    cpu_relax()
+#endif
+#ifndef arch_spin_relax
+# define arch_spin_relax(l)     cpu_relax()
+#endif
+
+/*
+ * We build the __lock_function inlines here. They are too large for
+ * inlining all over the place, but here is only one user per function
+ * which embedds them into the calling _lock_function below.
+ *
+ * This could be a long-held lock. We both prepare to spin for a long
+ * time (making _this_ CPU preemptable if possible), and we also signal
+ * towards that other CPU that it should break the lock ASAP.
+ */
+#define BUILD_LOCK_OPS(op, locktype)                                    \
+void __lockfunc __raw_##op##_lock(locktype##_t *lock)                   \
+{                                                                       \
+        for (;;) {                                                      \
+                preempt_disable();                                      \
+                if (likely(do_raw_##op##_trylock(lock)))                \
+                        break;                                          \
+                preempt_enable();                                       \
+                                                                        \
+                if (!(lock)->break_lock)                                \
+                        (lock)->break_lock = 1;                         \
+                while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
+                        arch_##op##_relax(&lock->raw_lock);             \
+        }                                                               \
+        (lock)->break_lock = 0;                                         \
+}                                                                       \
+                                                                        \
+unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock)  \
+{                                                                       \
+        unsigned long flags;                                            \
+                                                                        \
+        for (;;) {                                                      \
+                preempt_disable();                                      \
+                local_irq_save(flags);                                  \
+                if (likely(do_raw_##op##_trylock(lock)))                \
+                        break;                                          \
+                local_irq_restore(flags);                               \
+                preempt_enable();                                       \
+                                                                        \
+                if (!(lock)->break_lock)                                \
+                        (lock)->break_lock = 1;                         \
+                while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
+                        arch_##op##_relax(&lock->raw_lock);             \
+        }                                                               \
+        (lock)->break_lock = 0;                                         \
+        return flags;                                                   \
+}                                                                       \
+                                                                        \
+void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)               \
+{                                                                       \
+        _raw_##op##_lock_irqsave(lock);                                 \
+}                                                                       \
+                                                                        \
+void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock)                \
+{                                                                       \
+        unsigned long flags;                                            \
+                                                                        \
+        /*                                                      */      \
+        /* Careful: we must exclude softirqs too, hence the     */      \
+        /* irq-disabling. We use the generic preemption-aware   */      \
+        /* function:                                            */      \
+        /**/                                                            \
+        flags = _raw_##op##_lock_irqsave(lock);                         \
+        local_bh_disable();                                             \
+        local_irq_restore(flags);                                       \
+}                                                                       \
+
+/*
+ * Build preemption-friendly versions of the following
+ * lock-spinning functions:
+ *
+ *         __[spin|read|write]_lock()
+ *         __[spin|read|write]_lock_irq()
+ *         __[spin|read|write]_lock_irqsave()
+ *         __[spin|read|write]_lock_bh()
+ */
+BUILD_LOCK_OPS(spin, raw_spinlock);
+BUILD_LOCK_OPS(read, rwlock);
+BUILD_LOCK_OPS(write, rwlock);
+
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_TRYLOCK
+int __lockfunc _raw_spin_trylock(raw_spinlock_t *lock)
+{
+        return __raw_spin_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
+int __lockfunc _raw_spin_trylock_bh(raw_spinlock_t *lock)
+{
+        return __raw_spin_trylock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_trylock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK
+void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)
+{
+        __raw_spin_lock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_spin_lock_irqsave(raw_spinlock_t *lock)
+{
+        return __raw_spin_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
+void __lockfunc _raw_spin_lock_irq(raw_spinlock_t *lock)
+{
+        __raw_spin_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_LOCK_BH
+void __lockfunc _raw_spin_lock_bh(raw_spinlock_t *lock)
+{
+        __raw_spin_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_bh);
+#endif
+
+#ifdef CONFIG_UNINLINE_SPIN_UNLOCK
+void __lockfunc _raw_spin_unlock(raw_spinlock_t *lock)
+{
+        __raw_spin_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
+void __lockfunc _raw_spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
+{
+        __raw_spin_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
+void __lockfunc _raw_spin_unlock_irq(raw_spinlock_t *lock)
+{
+        __raw_spin_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
+void __lockfunc _raw_spin_unlock_bh(raw_spinlock_t *lock)
+{
+        __raw_spin_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_spin_unlock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_READ_TRYLOCK
+int __lockfunc _raw_read_trylock(rwlock_t *lock)
+{
+        return __raw_read_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_read_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK
+void __lockfunc _raw_read_lock(rwlock_t *lock)
+{
+        __raw_read_lock(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
+{
+        return __raw_read_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_IRQ
+void __lockfunc _raw_read_lock_irq(rwlock_t *lock)
+{
+        __raw_read_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_READ_LOCK_BH
+void __lockfunc _raw_read_lock_bh(rwlock_t *lock)
+{
+        __raw_read_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_read_lock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK
+void __lockfunc _raw_read_unlock(rwlock_t *lock)
+{
+        __raw_read_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
+void __lockfunc _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+{
+        __raw_read_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_read_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
+void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)
+{
+        __raw_read_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_READ_UNLOCK_BH
+void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)
+{
+        __raw_read_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_read_unlock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_TRYLOCK
+int __lockfunc _raw_write_trylock(rwlock_t *lock)
+{
+        return __raw_write_trylock(lock);
+}
+EXPORT_SYMBOL(_raw_write_trylock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK
+void __lockfunc _raw_write_lock(rwlock_t *lock)
+{
+        __raw_write_lock(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
+unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
+{
+        return __raw_write_lock_irqsave(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_irqsave);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
+void __lockfunc _raw_write_lock_irq(rwlock_t *lock)
+{
+        __raw_write_lock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_LOCK_BH
+void __lockfunc _raw_write_lock_bh(rwlock_t *lock)
+{
+        __raw_write_lock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_write_lock_bh);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK
+void __lockfunc _raw_write_unlock(rwlock_t *lock)
+{
+        __raw_write_unlock(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
+void __lockfunc _raw_write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+{
+        __raw_write_unlock_irqrestore(lock, flags);
+}
+EXPORT_SYMBOL(_raw_write_unlock_irqrestore);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
+void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)
+{
+        __raw_write_unlock_irq(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock_irq);
+#endif
+
+#ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
+void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)
+{
+        __raw_write_unlock_bh(lock);
+}
+EXPORT_SYMBOL(_raw_write_unlock_bh);
+#endif
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
+{
+        preempt_disable();
+        spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+        LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_nested);
+
+unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
+                                                   int subclass)
+{
+        unsigned long flags;
+
+        local_irq_save(flags);
+        preempt_disable();
+        spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+        LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
+                                do_raw_spin_lock_flags, &flags);
+        return flags;
+}
+EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);
+
+void __lockfunc _raw_spin_lock_nest_lock(raw_spinlock_t *lock,
+                                     struct lockdep_map *nest_lock)
+{
+        preempt_disable();
+        spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
+        LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
+}
+EXPORT_SYMBOL(_raw_spin_lock_nest_lock);
+
+#endif
+
+notrace int in_lock_functions(unsigned long addr)
+{
+        /* Linker adds these: start and end of __lockfunc functions */
+        extern char __lock_text_start[], __lock_text_end[];
+
+        return addr >= (unsigned long)__lock_text_start
+        && addr < (unsigned long)__lock_text_end;
+}
+EXPORT_SYMBOL(in_lock_functions);
diff --git a/kernel/locking/spinlock_debug.c b/kernel/locking/spinlock_debug.c
new file mode 100644
index 000000000000..0374a596cffa
--- /dev/null
+++ b/kernel/locking/spinlock_debug.c
@@ -0,0 +1,302 @@
+/*
+ * Copyright 2005, Red Hat, Inc., Ingo Molnar
+ * Released under the General Public License (GPL).
+ *
+ * This file contains the spinlock/rwlock implementations for
+ * DEBUG_SPINLOCK.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/nmi.h>
+#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+
+void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
+                          struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /*
+         * Make sure we are not reinitializing a held lock:
+         */
+        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+        lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+        lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+        lock->magic = SPINLOCK_MAGIC;
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+EXPORT_SYMBOL(__raw_spin_lock_init);
+
+void __rwlock_init(rwlock_t *lock, const char *name,
+                   struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /*
+         * Make sure we are not reinitializing a held lock:
+         */
+        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+        lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+        lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
+        lock->magic = RWLOCK_MAGIC;
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+EXPORT_SYMBOL(__rwlock_init);
+
+static void spin_dump(raw_spinlock_t *lock, const char *msg)
+{
+        struct task_struct *owner = NULL;
+
+        if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
+                owner = lock->owner;
+        printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
+                msg, raw_smp_processor_id(),
+                current->comm, task_pid_nr(current));
+        printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
+                        ".owner_cpu: %d\n",
+                lock, lock->magic,
+                owner ? owner->comm : "<none>",
+                owner ? task_pid_nr(owner) : -1,
+                lock->owner_cpu);
+        dump_stack();
+}
+
+static void spin_bug(raw_spinlock_t *lock, const char *msg)
+{
+        if (!debug_locks_off())
+                return;
+
+        spin_dump(lock, msg);
+}
+
+#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
+
+static inline void
+debug_spin_lock_before(raw_spinlock_t *lock)
+{
+        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+        SPIN_BUG_ON(lock->owner == current, lock, "recursion");
+        SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+                                                        lock, "cpu recursion");
+}
+
+static inline void debug_spin_lock_after(raw_spinlock_t *lock)
+{
+        lock->owner_cpu = raw_smp_processor_id();
+        lock->owner = current;
+}
+
+static inline void debug_spin_unlock(raw_spinlock_t *lock)
+{
+        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+        SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
+        SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
+        SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+                                                        lock, "wrong CPU");
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+static void __spin_lock_debug(raw_spinlock_t *lock)
+{
+        u64 i;
+        u64 loops = loops_per_jiffy * HZ;
+
+        for (i = 0; i < loops; i++) {
+                if (arch_spin_trylock(&lock->raw_lock))
+                        return;
+                __delay(1);
+        }
+        /* lockup suspected: */
+        spin_dump(lock, "lockup suspected");
+#ifdef CONFIG_SMP
+        trigger_all_cpu_backtrace();
+#endif
+
+        /*
+         * The trylock above was causing a livelock.  Give the lower level arch
+         * specific lock code a chance to acquire the lock. We have already
+         * printed a warning/backtrace at this point. The non-debug arch
+         * specific code might actually succeed in acquiring the lock.  If it is
+         * not successful, the end-result is the same - there is no forward
+         * progress.
+         */
+        arch_spin_lock(&lock->raw_lock);
+}
+
+void do_raw_spin_lock(raw_spinlock_t *lock)
+{
+        debug_spin_lock_before(lock);
+        if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
+                __spin_lock_debug(lock);
+        debug_spin_lock_after(lock);
+}
+
+int do_raw_spin_trylock(raw_spinlock_t *lock)
+{
+        int ret = arch_spin_trylock(&lock->raw_lock);
+
+        if (ret)
+                debug_spin_lock_after(lock);
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void do_raw_spin_unlock(raw_spinlock_t *lock)
+{
+        debug_spin_unlock(lock);
+        arch_spin_unlock(&lock->raw_lock);
+}
+
+static void rwlock_bug(rwlock_t *lock, const char *msg)
+{
+        if (!debug_locks_off())
+                return;
+
+        printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
+                msg, raw_smp_processor_id(), current->comm,
+                task_pid_nr(current), lock);
+        dump_stack();
+}
+
+#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
+
+#if 0           /* __write_lock_debug() can lock up - maybe this can too? */
+static void __read_lock_debug(rwlock_t *lock)
+{
+        u64 i;
+        u64 loops = loops_per_jiffy * HZ;
+        int print_once = 1;
+
+        for (;;) {
+                for (i = 0; i < loops; i++) {
+                        if (arch_read_trylock(&lock->raw_lock))
+                                return;
+                        __delay(1);
+                }
+                /* lockup suspected: */
+                if (print_once) {
+                        print_once = 0;
+                        printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
+                                        "%s/%d, %p\n",
+                                raw_smp_processor_id(), current->comm,
+                                current->pid, lock);
+                        dump_stack();
+                }
+        }
+}
+#endif
+
+void do_raw_read_lock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        arch_read_lock(&lock->raw_lock);
+}
+
+int do_raw_read_trylock(rwlock_t *lock)
+{
+        int ret = arch_read_trylock(&lock->raw_lock);
+
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void do_raw_read_unlock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        arch_read_unlock(&lock->raw_lock);
+}
+
+static inline void debug_write_lock_before(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
+        RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+                                                        lock, "cpu recursion");
+}
+
+static inline void debug_write_lock_after(rwlock_t *lock)
+{
+        lock->owner_cpu = raw_smp_processor_id();
+        lock->owner = current;
+}
+
+static inline void debug_write_unlock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
+        RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+                                                        lock, "wrong CPU");
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+#if 0           /* This can cause lockups */
+static void __write_lock_debug(rwlock_t *lock)
+{
+        u64 i;
+        u64 loops = loops_per_jiffy * HZ;
+        int print_once = 1;
+
+        for (;;) {
+                for (i = 0; i < loops; i++) {
+                        if (arch_write_trylock(&lock->raw_lock))
+                                return;
+                        __delay(1);
+                }
+                /* lockup suspected: */
+                if (print_once) {
+                        print_once = 0;
+                        printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
+                                        "%s/%d, %p\n",
+                                raw_smp_processor_id(), current->comm,
+                                current->pid, lock);
+                        dump_stack();
+                }
+        }
+}
+#endif
+
+void do_raw_write_lock(rwlock_t *lock)
+{
+        debug_write_lock_before(lock);
+        arch_write_lock(&lock->raw_lock);
+        debug_write_lock_after(lock);
+}
+
+int do_raw_write_trylock(rwlock_t *lock)
+{
+        int ret = arch_write_trylock(&lock->raw_lock);
+
+        if (ret)
+                debug_write_lock_after(lock);
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void do_raw_write_unlock(rwlock_t *lock)
+{
+        debug_write_unlock(lock);
+        arch_write_unlock(&lock->raw_lock);
+}