Root/kernel/mutex-debug.c

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/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 (unlikely(!debug_locks))
75        return;
76
77    DEBUG_LOCKS_WARN_ON(lock->magic != lock);
78    DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
79    DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
80    mutex_clear_owner(lock);
81}
82
83void debug_mutex_init(struct mutex *lock, const char *name,
84              struct lock_class_key *key)
85{
86#ifdef CONFIG_DEBUG_LOCK_ALLOC
87    /*
88     * Make sure we are not reinitializing a held lock:
89     */
90    debug_check_no_locks_freed((void *)lock, sizeof(*lock));
91    lockdep_init_map(&lock->dep_map, name, key, 0);
92#endif
93    lock->magic = lock;
94}
95
96/***
97 * mutex_destroy - mark a mutex unusable
98 * @lock: the mutex to be destroyed
99 *
100 * This function marks the mutex uninitialized, and any subsequent
101 * use of the mutex is forbidden. The mutex must not be locked when
102 * this function is called.
103 */
104void mutex_destroy(struct mutex *lock)
105{
106    DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
107    lock->magic = NULL;
108}
109
110EXPORT_SYMBOL_GPL(mutex_destroy);
111

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