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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 */
30 void 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
37 void 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
45 void 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
51 void 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
60 void 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
72 void 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 && !lock->wait_list.next);
83 }
84
85 /*
86 * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug
87 * mutexes so that we can do it here after we've verified state.
88 */
89 mutex_clear_owner(lock);
90 atomic_set(&lock->count, 1);
91 }
92
93 void debug_mutex_init(struct mutex *lock, const char *name,
94 struct lock_class_key *key)
95 {
96 #ifdef CONFIG_DEBUG_LOCK_ALLOC
97 /*
98 * Make sure we are not reinitializing a held lock:
99 */
100 debug_check_no_locks_freed((void *)lock, sizeof(*lock));
101 lockdep_init_map(&lock->dep_map, name, key, 0);
102 #endif
103 lock->magic = lock;
104 }
105
106 /***
107 * mutex_destroy - mark a mutex unusable
108 * @lock: the mutex to be destroyed
109 *
110 * This function marks the mutex uninitialized, and any subsequent
111 * use of the mutex is forbidden. The mutex must not be locked when
112 * this function is called.
113 */
114 void mutex_destroy(struct mutex *lock)
115 {
116 DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
117 lock->magic = NULL;
118 }
119
120 EXPORT_SYMBOL_GPL(mutex_destroy);