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_set_owner(struct mutex *lock, struct thread_info *new_owner)
  30{
  31        lock->owner = new_owner;
  32}
  33
  34void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  35{
  36        memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  37        waiter->magic = waiter;
  38        INIT_LIST_HEAD(&waiter->list);
  39}
  40
  41void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  42{
  43        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  44        DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  45        DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  46        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  47}
  48
  49void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  50{
  51        DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  52        memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  53}
  54
  55void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  56                            struct thread_info *ti)
  57{
  58        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  59
  60        /* Mark the current thread as blocked on the lock: */
  61        ti->task->blocked_on = waiter;
  62        waiter->lock = lock;
  63}
  64
  65void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  66                         struct thread_info *ti)
  67{
  68        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  69        DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
  70        DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
  71        ti->task->blocked_on = NULL;
  72
  73        list_del_init(&waiter->list);
  74        waiter->task = NULL;
  75}
  76
  77void debug_mutex_unlock(struct mutex *lock)
  78{
  79        if (unlikely(!debug_locks))
  80                return;
  81
  82        DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  83        DEBUG_LOCKS_WARN_ON(lock->magic != lock);
  84        DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
  85        DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  86}
  87
  88void debug_mutex_init(struct mutex *lock, const char *name,
  89                      struct lock_class_key *key)
  90{
  91#ifdef CONFIG_DEBUG_LOCK_ALLOC
  92        /*
  93         * Make sure we are not reinitializing a held lock:
  94         */
  95        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  96        lockdep_init_map(&lock->dep_map, name, key, 0);
  97#endif
  98        lock->owner = NULL;
  99        lock->magic = lock;
 100}
 101
 102/***
 103 * mutex_destroy - mark a mutex unusable
 104 * @lock: the mutex to be destroyed
 105 *
 106 * This function marks the mutex uninitialized, and any subsequent
 107 * use of the mutex is forbidden. The mutex must not be locked when
 108 * this function is called.
 109 */
 110void mutex_destroy(struct mutex *lock)
 111{
 112        DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 113        lock->magic = NULL;
 114}
 115
 116EXPORT_SYMBOL_GPL(mutex_destroy);
 117