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/device.h>
16 #include <linux/export.h>
17 #include <linux/poison.h>
18 #include <linux/sched.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.h"
25
26 /*
27 * Must be called with lock->wait_lock held.
28 */
debug_mutex_lock_common(struct mutex * lock,struct mutex_waiter * waiter)29 void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
30 {
31 memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
32 waiter->magic = waiter;
33 INIT_LIST_HEAD(&waiter->list);
34 waiter->ww_ctx = MUTEX_POISON_WW_CTX;
35 }
36
debug_mutex_wake_waiter(struct mutex * lock,struct mutex_waiter * waiter)37 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
38 {
39 lockdep_assert_held(&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
debug_mutex_free_waiter(struct mutex_waiter * waiter)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
debug_mutex_add_waiter(struct mutex * lock,struct mutex_waiter * waiter,struct task_struct * task)51 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
52 struct task_struct *task)
53 {
54 lockdep_assert_held(&lock->wait_lock);
55
56 /* Mark the current thread as blocked on the lock: */
57 task->blocked_on = waiter;
58 }
59
debug_mutex_remove_waiter(struct mutex * lock,struct mutex_waiter * waiter,struct task_struct * task)60 void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
61 struct task_struct *task)
62 {
63 DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
64 DEBUG_LOCKS_WARN_ON(waiter->task != task);
65 DEBUG_LOCKS_WARN_ON(task->blocked_on != waiter);
66 task->blocked_on = NULL;
67
68 INIT_LIST_HEAD(&waiter->list);
69 waiter->task = NULL;
70 }
71
debug_mutex_unlock(struct mutex * lock)72 void debug_mutex_unlock(struct mutex *lock)
73 {
74 if (likely(debug_locks)) {
75 DEBUG_LOCKS_WARN_ON(lock->magic != lock);
76 DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
77 }
78 }
79
debug_mutex_init(struct mutex * lock,const char * name,struct lock_class_key * key)80 void debug_mutex_init(struct mutex *lock, const char *name,
81 struct lock_class_key *key)
82 {
83 #ifdef CONFIG_DEBUG_LOCK_ALLOC
84 /*
85 * Make sure we are not reinitializing a held lock:
86 */
87 debug_check_no_locks_freed((void *)lock, sizeof(*lock));
88 lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);
89 #endif
90 lock->magic = lock;
91 }
92
devm_mutex_release(void * res)93 static void devm_mutex_release(void *res)
94 {
95 mutex_destroy(res);
96 }
97
__devm_mutex_init(struct device * dev,struct mutex * lock)98 int __devm_mutex_init(struct device *dev, struct mutex *lock)
99 {
100 return devm_add_action_or_reset(dev, devm_mutex_release, lock);
101 }
102 EXPORT_SYMBOL_GPL(__devm_mutex_init);
103
104 /***
105 * mutex_destroy - mark a mutex unusable
106 * @lock: the mutex to be destroyed
107 *
108 * This function marks the mutex uninitialized, and any subsequent
109 * use of the mutex is forbidden. The mutex must not be locked when
110 * this function is called.
111 */
mutex_destroy(struct mutex * lock)112 void mutex_destroy(struct mutex *lock)
113 {
114 DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
115 lock->magic = NULL;
116 }
117
118 EXPORT_SYMBOL_GPL(mutex_destroy);
119