xref: /openbmc/linux/kernel/locking/mutex-debug.c (revision b34e08d5)
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  */
30 void 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 
37 void 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 
45 void 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 
51 void 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 
60 void 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 
72 void debug_mutex_unlock(struct mutex *lock)
73 {
74 	if (unlikely(!debug_locks))
75 		return;
76 
77 	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
78 
79 	if (!lock->owner)
80 		DEBUG_LOCKS_WARN_ON(!lock->owner);
81 	else
82 		DEBUG_LOCKS_WARN_ON(lock->owner != current);
83 
84 	DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
85 	mutex_clear_owner(lock);
86 
87 	/*
88 	 * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug
89 	 * mutexes so that we can do it here after we've verified state.
90 	 */
91 	atomic_set(&lock->count, 1);
92 }
93 
94 void debug_mutex_init(struct mutex *lock, const char *name,
95 		      struct lock_class_key *key)
96 {
97 #ifdef CONFIG_DEBUG_LOCK_ALLOC
98 	/*
99 	 * Make sure we are not reinitializing a held lock:
100 	 */
101 	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
102 	lockdep_init_map(&lock->dep_map, name, key, 0);
103 #endif
104 	lock->magic = lock;
105 }
106 
107 /***
108  * mutex_destroy - mark a mutex unusable
109  * @lock: the mutex to be destroyed
110  *
111  * This function marks the mutex uninitialized, and any subsequent
112  * use of the mutex is forbidden. The mutex must not be locked when
113  * this function is called.
114  */
115 void mutex_destroy(struct mutex *lock)
116 {
117 	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
118 	lock->magic = NULL;
119 }
120 
121 EXPORT_SYMBOL_GPL(mutex_destroy);
122