root/lib/spinlock_debug.c

DEFINITIONS

1. __spin_lock_init
2. __rwlock_init
3. spin_bug
4. debug_spin_lock_before
5. debug_spin_lock_after
6. debug_spin_unlock
7. __spin_lock_debug
8. _raw_spin_lock
9. _raw_spin_trylock
10. _raw_spin_unlock
11. rwlock_bug
12. __read_lock_debug
13. _raw_read_lock
14. _raw_read_trylock
15. _raw_read_unlock
16. debug_write_lock_before
17. debug_write_lock_after
18. debug_write_unlock
19. __write_lock_debug
20. _raw_write_lock
21. _raw_write_trylock
22. _raw_write_unlock

/*
 * 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/module.h>

void __spin_lock_init(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 = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
        lock->magic = SPINLOCK_MAGIC;
        lock->owner = SPINLOCK_OWNER_INIT;
        lock->owner_cpu = -1;
}

EXPORT_SYMBOL(__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 = (raw_rwlock_t) __RAW_RW_LOCK_UNLOCKED;
        lock->magic = RWLOCK_MAGIC;
        lock->owner = SPINLOCK_OWNER_INIT;
        lock->owner_cpu = -1;
}

EXPORT_SYMBOL(__rwlock_init);

static void spin_bug(spinlock_t *lock, const char *msg)
{
        struct task_struct *owner = NULL;

        if (!debug_locks_off())
                return;

        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: %p, .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();
}

#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)

static inline void
debug_spin_lock_before(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(spinlock_t *lock)
{
        lock->owner_cpu = raw_smp_processor_id();
        lock->owner = current;
}

static inline void debug_spin_unlock(spinlock_t *lock)
{
        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
        SPIN_BUG_ON(!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(spinlock_t *lock)
{
        u64 i;
        u64 loops = loops_per_jiffy * HZ;
        int print_once = 1;

        for (;;) {
                for (i = 0; i < loops; i++) {
                        if (__raw_spin_trylock(&lock->raw_lock))
                                return;
                        __delay(1);
                }
                /* lockup suspected: */
                if (print_once) {
                        print_once = 0;
                        printk(KERN_EMERG "BUG: spinlock lockup on CPU#%d, "
                                        "%s/%d, %p\n",
                                raw_smp_processor_id(), current->comm,
                                task_pid_nr(current), lock);
                        dump_stack();
#ifdef CONFIG_SMP
                        trigger_all_cpu_backtrace();
#endif
                }
        }
}

void _raw_spin_lock(spinlock_t *lock)
{
        debug_spin_lock_before(lock);
        if (unlikely(!__raw_spin_trylock(&lock->raw_lock)))
                __spin_lock_debug(lock);
        debug_spin_lock_after(lock);
}

int _raw_spin_trylock(spinlock_t *lock)
{
        int ret = __raw_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 _raw_spin_unlock(spinlock_t *lock)
{
        debug_spin_unlock(lock);
        __raw_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 (__raw_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 _raw_read_lock(rwlock_t *lock)
{
        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
        __raw_read_lock(&lock->raw_lock);
}

int _raw_read_trylock(rwlock_t *lock)
{
        int ret = __raw_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 _raw_read_unlock(rwlock_t *lock)
{
        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
        __raw_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 (__raw_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 _raw_write_lock(rwlock_t *lock)
{
        debug_write_lock_before(lock);
        __raw_write_lock(&lock->raw_lock);
        debug_write_lock_after(lock);
}

int _raw_write_trylock(rwlock_t *lock)
{
        int ret = __raw_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 _raw_write_unlock(rwlock_t *lock)
{
        debug_write_unlock(lock);
        __raw_write_unlock(&lock->raw_lock);
}