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 */
29void debug_mutex_set_owner(struct mutex *lock, struct thread_info *new_owner)
30{
31	lock->owner = new_owner;
32}
33
34void 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
41void 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
49void 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
55void 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
65void 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
77void debug_mutex_unlock(struct mutex *lock)
78{
79	if (unlikely(!debug_locks))
80		return;
81
82	DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
83	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
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
88void 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 */
110void fastcall mutex_destroy(struct mutex *lock)
111{
112	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
113	lock->magic = NULL;
114}
115
116EXPORT_SYMBOL_GPL(mutex_destroy);
117