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