LXR linux/kernel/mutex-debug.c

   1/*
   2 * kernel/mutex-debug.c
   3 *
   4 * Debugging code for mutexes
   5 *
   6 * Started by Ingo Molnar:
   7 *
   8 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   9 *
  10 * lock debugging, locking tree, deadlock detection started by:
  11 *
  12 *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
  13 *  Released under the General Public License (GPL).
  14 */
  15#include <linux/mutex.h>
  16#include <linux/delay.h>
  17#include <linux/module.h>
  18#include <linux/poison.h>
  19#include <linux/spinlock.h>
  20#include <linux/kallsyms.h>
  21#include <linux/interrupt.h>
  22#include <linux/debug_locks.h>
  23
  24#include "mutex-debug.h"
  25
  26/*
  27 * Must be called with lock->wait_lock held.
  28 */
  29void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  30{
  31        memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  32        waiter->magic = waiter;
  33        INIT_LIST_HEAD(&waiter->list);
  34}
  35
  36void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  37{
  38        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  39        DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  40        DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  41        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  42}
  43
  44void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  45{
  46        DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  47        memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  48}
  49
  50void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  51                            struct thread_info *ti)
  52{
  53        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  54
  55        /* Mark the current thread as blocked on the lock: */
  56        ti->task->blocked_on = waiter;
  57}
  58
  59void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  60                         struct thread_info *ti)
  61{
  62        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  63        DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
  64        DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
  65        ti->task->blocked_on = NULL;
  66
  67        list_del_init(&waiter->list);
  68        waiter->task = NULL;
  69}
  70
  71void debug_mutex_unlock(struct mutex *lock)
  72{
  73        if (unlikely(!debug_locks))
  74                return;
  75
  76        DEBUG_LOCKS_WARN_ON(lock->magic != lock);
  77        DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  78        DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
  79        mutex_clear_owner(lock);
  80}
  81
  82void debug_mutex_init(struct mutex *lock, const char *name,
  83                      struct lock_class_key *key)
  84{
  85#ifdef CONFIG_DEBUG_LOCK_ALLOC
  86        /*
  87         * Make sure we are not reinitializing a held lock:
  88         */
  89        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  90        lockdep_init_map(&lock->dep_map, name, key, 0);
  91#endif
  92        lock->magic = lock;
  93}
  94
  95/***
  96 * mutex_destroy - mark a mutex unusable
  97 * @lock: the mutex to be destroyed
  98 *
  99 * This function marks the mutex uninitialized, and any subsequent
 100 * use of the mutex is forbidden. The mutex must not be locked when
 101 * this function is called.
 102 */
 103void mutex_destroy(struct mutex *lock)
 104{
 105        DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 106        lock->magic = NULL;
 107}
 108
 109EXPORT_SYMBOL_GPL(mutex_destroy);
 110