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 */
30void 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
37void 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
45void 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
51void 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
60void 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
72void 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
93void 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 */
114void mutex_destroy(struct mutex *lock)
115{
116	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
117	lock->magic = NULL;
118}
119
120EXPORT_SYMBOL_GPL(mutex_destroy);
121