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6053ee3b IM |
1 | /* |
2 | * Mutexes: blocking mutual exclusion locks | |
3 | * | |
4 | * started by Ingo Molnar: | |
5 | * | |
6 | * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
7 | * | |
8 | * This file contains the main data structure and API definitions. | |
9 | */ | |
10 | #ifndef __LINUX_MUTEX_H | |
11 | #define __LINUX_MUTEX_H | |
12 | ||
040a0a37 | 13 | #include <asm/current.h> |
6053ee3b IM |
14 | #include <linux/list.h> |
15 | #include <linux/spinlock_types.h> | |
a8b9ee73 | 16 | #include <linux/linkage.h> |
ef5d4707 | 17 | #include <linux/lockdep.h> |
60063497 | 18 | #include <linux/atomic.h> |
083986e8 | 19 | #include <asm/processor.h> |
90631822 | 20 | #include <linux/osq_lock.h> |
3ca0ff57 | 21 | #include <linux/debug_locks.h> |
6053ee3b IM |
22 | |
23 | /* | |
24 | * Simple, straightforward mutexes with strict semantics: | |
25 | * | |
26 | * - only one task can hold the mutex at a time | |
27 | * - only the owner can unlock the mutex | |
28 | * - multiple unlocks are not permitted | |
29 | * - recursive locking is not permitted | |
30 | * - a mutex object must be initialized via the API | |
31 | * - a mutex object must not be initialized via memset or copying | |
32 | * - task may not exit with mutex held | |
33 | * - memory areas where held locks reside must not be freed | |
34 | * - held mutexes must not be reinitialized | |
f20fda48 ML |
35 | * - mutexes may not be used in hardware or software interrupt |
36 | * contexts such as tasklets and timers | |
6053ee3b IM |
37 | * |
38 | * These semantics are fully enforced when DEBUG_MUTEXES is | |
39 | * enabled. Furthermore, besides enforcing the above rules, the mutex | |
40 | * debugging code also implements a number of additional features | |
41 | * that make lock debugging easier and faster: | |
42 | * | |
43 | * - uses symbolic names of mutexes, whenever they are printed in debug output | |
44 | * - point-of-acquire tracking, symbolic lookup of function names | |
45 | * - list of all locks held in the system, printout of them | |
46 | * - owner tracking | |
47 | * - detects self-recursing locks and prints out all relevant info | |
48 | * - detects multi-task circular deadlocks and prints out all affected | |
49 | * locks and tasks (and only those tasks) | |
50 | */ | |
51 | struct mutex { | |
3ca0ff57 | 52 | atomic_long_t owner; |
6053ee3b | 53 | spinlock_t wait_lock; |
2bd2c92c | 54 | #ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
90631822 | 55 | struct optimistic_spin_queue osq; /* Spinner MCS lock */ |
2bd2c92c | 56 | #endif |
3ca0ff57 | 57 | struct list_head wait_list; |
0d66bf6d | 58 | #ifdef CONFIG_DEBUG_MUTEXES |
6053ee3b IM |
59 | void *magic; |
60 | #endif | |
ef5d4707 IM |
61 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
62 | struct lockdep_map dep_map; | |
63 | #endif | |
6053ee3b IM |
64 | }; |
65 | ||
3ca0ff57 PZ |
66 | static inline struct task_struct *__mutex_owner(struct mutex *lock) |
67 | { | |
68 | return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x03); | |
69 | } | |
70 | ||
6053ee3b IM |
71 | /* |
72 | * This is the control structure for tasks blocked on mutex, | |
73 | * which resides on the blocked task's kernel stack: | |
74 | */ | |
75 | struct mutex_waiter { | |
76 | struct list_head list; | |
77 | struct task_struct *task; | |
78 | #ifdef CONFIG_DEBUG_MUTEXES | |
6053ee3b IM |
79 | void *magic; |
80 | #endif | |
81 | }; | |
82 | ||
83 | #ifdef CONFIG_DEBUG_MUTEXES | |
3ca0ff57 PZ |
84 | |
85 | #define __DEBUG_MUTEX_INITIALIZER(lockname) \ | |
86 | , .magic = &lockname | |
87 | ||
88 | extern void mutex_destroy(struct mutex *lock); | |
89 | ||
6053ee3b | 90 | #else |
3ca0ff57 | 91 | |
6053ee3b | 92 | # define __DEBUG_MUTEX_INITIALIZER(lockname) |
3ca0ff57 PZ |
93 | |
94 | static inline void mutex_destroy(struct mutex *lock) {} | |
95 | ||
96 | #endif | |
97 | ||
ef5dc121 RD |
98 | /** |
99 | * mutex_init - initialize the mutex | |
100 | * @mutex: the mutex to be initialized | |
101 | * | |
102 | * Initialize the mutex to unlocked state. | |
103 | * | |
104 | * It is not allowed to initialize an already locked mutex. | |
105 | */ | |
3ca0ff57 PZ |
106 | #define mutex_init(mutex) \ |
107 | do { \ | |
108 | static struct lock_class_key __key; \ | |
109 | \ | |
110 | __mutex_init((mutex), #mutex, &__key); \ | |
ef5d4707 | 111 | } while (0) |
6053ee3b | 112 | |
ef5d4707 IM |
113 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
114 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ | |
115 | , .dep_map = { .name = #lockname } | |
116 | #else | |
117 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) | |
118 | #endif | |
119 | ||
6053ee3b | 120 | #define __MUTEX_INITIALIZER(lockname) \ |
3ca0ff57 | 121 | { .owner = ATOMIC_LONG_INIT(0) \ |
6cfd76a2 | 122 | , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ |
6053ee3b | 123 | , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ |
ef5d4707 IM |
124 | __DEBUG_MUTEX_INITIALIZER(lockname) \ |
125 | __DEP_MAP_MUTEX_INITIALIZER(lockname) } | |
6053ee3b IM |
126 | |
127 | #define DEFINE_MUTEX(mutexname) \ | |
128 | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) | |
129 | ||
ef5d4707 IM |
130 | extern void __mutex_init(struct mutex *lock, const char *name, |
131 | struct lock_class_key *key); | |
6053ee3b | 132 | |
45f8bde0 | 133 | /** |
6053ee3b IM |
134 | * mutex_is_locked - is the mutex locked |
135 | * @lock: the mutex to be queried | |
136 | * | |
137 | * Returns 1 if the mutex is locked, 0 if unlocked. | |
138 | */ | |
ec701584 | 139 | static inline int mutex_is_locked(struct mutex *lock) |
6053ee3b | 140 | { |
3ca0ff57 PZ |
141 | /* |
142 | * XXX think about spin_is_locked | |
143 | */ | |
144 | return __mutex_owner(lock) != NULL; | |
6053ee3b IM |
145 | } |
146 | ||
147 | /* | |
67a6de49 | 148 | * See kernel/locking/mutex.c for detailed documentation of these APIs. |
214e0aed | 149 | * Also see Documentation/locking/mutex-design.txt. |
6053ee3b | 150 | */ |
ef5d4707 IM |
151 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
152 | extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); | |
e4c70a66 | 153 | extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
040a0a37 | 154 | |
18d8362d AM |
155 | extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
156 | unsigned int subclass); | |
ad776537 LH |
157 | extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
158 | unsigned int subclass); | |
e4564f79 PZ |
159 | |
160 | #define mutex_lock(lock) mutex_lock_nested(lock, 0) | |
161 | #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) | |
ad776537 | 162 | #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
e4c70a66 PZ |
163 | |
164 | #define mutex_lock_nest_lock(lock, nest_lock) \ | |
165 | do { \ | |
040a0a37 | 166 | typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ |
e4c70a66 PZ |
167 | _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ |
168 | } while (0) | |
169 | ||
ef5d4707 | 170 | #else |
ec701584 HH |
171 | extern void mutex_lock(struct mutex *lock); |
172 | extern int __must_check mutex_lock_interruptible(struct mutex *lock); | |
173 | extern int __must_check mutex_lock_killable(struct mutex *lock); | |
e4564f79 | 174 | |
ef5d4707 | 175 | # define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
d63a5a74 | 176 | # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
ad776537 | 177 | # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
e4c70a66 | 178 | # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
ef5d4707 IM |
179 | #endif |
180 | ||
6053ee3b IM |
181 | /* |
182 | * NOTE: mutex_trylock() follows the spin_trylock() convention, | |
183 | * not the down_trylock() convention! | |
d98d38f2 AV |
184 | * |
185 | * Returns 1 if the mutex has been acquired successfully, and 0 on contention. | |
6053ee3b | 186 | */ |
ec701584 HH |
187 | extern int mutex_trylock(struct mutex *lock); |
188 | extern void mutex_unlock(struct mutex *lock); | |
040a0a37 | 189 | |
a511e3f9 | 190 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
b1fca266 | 191 | |
e7224674 | 192 | #endif /* __LINUX_MUTEX_H */ |