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 */
debug_mutex_set_owner(struct mutex * lock,struct thread_info * new_owner)29 void debug_mutex_set_owner(struct mutex *lock, struct thread_info *new_owner)
30 {
31 lock->owner = new_owner;
32 }
33
debug_mutex_lock_common(struct mutex * lock,struct mutex_waiter * waiter)34 void 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
debug_mutex_wake_waiter(struct mutex * lock,struct mutex_waiter * waiter)41 void 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
debug_mutex_free_waiter(struct mutex_waiter * waiter)49 void 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
debug_mutex_add_waiter(struct mutex * lock,struct mutex_waiter * waiter,struct thread_info * ti)55 void 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
mutex_remove_waiter(struct mutex * lock,struct mutex_waiter * waiter,struct thread_info * ti)65 void 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
debug_mutex_unlock(struct mutex * lock)77 void debug_mutex_unlock(struct mutex *lock)
78 {
79 if (unlikely(!debug_locks))
80 return;
81
82 DEBUG_LOCKS_WARN_ON(lock->magic != lock);
83 DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
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
debug_mutex_init(struct mutex * lock,const char * name,struct lock_class_key * key)88 void 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 */
mutex_destroy(struct mutex * lock)110 void mutex_destroy(struct mutex *lock)
111 {
112 DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
113 lock->magic = NULL;
114 }
115
116 EXPORT_SYMBOL_GPL(mutex_destroy);
117