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 */
28void 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
36void 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
44void 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
50void 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
59void 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
71void 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
79void 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 */
100void mutex_destroy(struct mutex *lock)
101{
102	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
103	lock->magic = NULL;
104}
105
106EXPORT_SYMBOL_GPL(mutex_destroy);
107