LXR linux/kernel/locking/mutex-debug.c

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