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(list: &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(list: &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(from: (void *)lock, len: sizeof(*lock));
87 lockdep_init_map_wait(lock: &lock->dep_map, name, key, subclass: 0, inner: 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

source code of linux/kernel/locking/mutex-debug.c