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/export.h>
  18#include <linux/poison.h>
  19#include <linux/sched.h>
  20#include <linux/spinlock.h>
  21#include <linux/kallsyms.h>
  22#include <linux/interrupt.h>
  23#include <linux/debug_locks.h>
  24
  25#include "mutex-debug.h"
  26
  27/*
  28 * Must be called with lock->wait_lock held.
  29 */
  30void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  31{
  32        memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  33        waiter->magic = waiter;
  34        INIT_LIST_HEAD(&waiter->list);
  35}
  36
  37void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  38{
  39        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  40        DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  41        DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  42        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  43}
  44
  45void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  46{
  47        DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  48        memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  49}
  50
  51void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  52                            struct thread_info *ti)
  53{
  54        SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  55
  56        /* Mark the current thread as blocked on the lock: */
  57        ti->task->blocked_on = waiter;
  58}
  59
  60void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  61                         struct thread_info *ti)
  62{
  63        DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  64        DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
  65        DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
  66        ti->task->blocked_on = NULL;
  67
  68        list_del_init(&waiter->list);
  69        waiter->task = NULL;
  70}
  71
  72void debug_mutex_unlock(struct mutex *lock)
  73{
  74        if (likely(debug_locks)) {
  75                DEBUG_LOCKS_WARN_ON(lock->magic != lock);
  76
  77                if (!lock->owner)
  78                        DEBUG_LOCKS_WARN_ON(!lock->owner);
  79                else
  80                        DEBUG_LOCKS_WARN_ON(lock->owner != current);
  81
  82                DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev &&
  83                                    !lock->wait_list.next);
  84                mutex_clear_owner(lock);
  85        }
  86
  87        /*
  88         * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug
  89         * mutexes so that we can do it here after we've verified state.
  90         */
  91        atomic_set(&lock->count, 1);
  92}
  93
  94void debug_mutex_init(struct mutex *lock, const char *name,
  95                      struct lock_class_key *key)
  96{
  97#ifdef CONFIG_DEBUG_LOCK_ALLOC
  98        /*
  99         * Make sure we are not reinitializing a held lock:
 100         */
 101        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 102        lockdep_init_map(&lock->dep_map, name, key, 0);
 103#endif
 104        lock->magic = lock;
 105}
 106
 107/***
 108 * mutex_destroy - mark a mutex unusable
 109 * @lock: the mutex to be destroyed
 110 *
 111 * This function marks the mutex uninitialized, and any subsequent
 112 * use of the mutex is forbidden. The mutex must not be locked when
 113 * this function is called.
 114 */
 115void mutex_destroy(struct mutex *lock)
 116{
 117        DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 118        lock->magic = NULL;
 119}
 120
 121EXPORT_SYMBOL_GPL(mutex_destroy);
 122