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 */
debug_mutex_lock_common(struct mutex * lock,struct mutex_waiter * waiter)28 void 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
debug_mutex_wake_waiter(struct mutex * lock,struct mutex_waiter * waiter)36 void 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
debug_mutex_free_waiter(struct mutex_waiter * waiter)44 void 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
debug_mutex_add_waiter(struct mutex * lock,struct mutex_waiter * waiter,struct task_struct * task)50 void 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
debug_mutex_remove_waiter(struct mutex * lock,struct mutex_waiter * waiter,struct task_struct * task)59 void 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
debug_mutex_unlock(struct mutex * lock)71 void 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
debug_mutex_init(struct mutex * lock,const char * name,struct lock_class_key * key)79 void 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 */
mutex_destroy(struct mutex * lock)100 void mutex_destroy(struct mutex *lock)
101 {
102 DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
103 lock->magic = NULL;
104 }
105
106 EXPORT_SYMBOL_GPL(mutex_destroy);
107