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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 | ||
13 | #include <linux/list.h> | |
14 | #include <linux/spinlock_types.h> | |
a8b9ee73 | 15 | #include <linux/linkage.h> |
ef5d4707 | 16 | #include <linux/lockdep.h> |
6053ee3b | 17 | |
60063497 | 18 | #include <linux/atomic.h> |
6053ee3b IM |
19 | |
20 | /* | |
21 | * Simple, straightforward mutexes with strict semantics: | |
22 | * | |
23 | * - only one task can hold the mutex at a time | |
24 | * - only the owner can unlock the mutex | |
25 | * - multiple unlocks are not permitted | |
26 | * - recursive locking is not permitted | |
27 | * - a mutex object must be initialized via the API | |
28 | * - a mutex object must not be initialized via memset or copying | |
29 | * - task may not exit with mutex held | |
30 | * - memory areas where held locks reside must not be freed | |
31 | * - held mutexes must not be reinitialized | |
f20fda48 ML |
32 | * - mutexes may not be used in hardware or software interrupt |
33 | * contexts such as tasklets and timers | |
6053ee3b IM |
34 | * |
35 | * These semantics are fully enforced when DEBUG_MUTEXES is | |
36 | * enabled. Furthermore, besides enforcing the above rules, the mutex | |
37 | * debugging code also implements a number of additional features | |
38 | * that make lock debugging easier and faster: | |
39 | * | |
40 | * - uses symbolic names of mutexes, whenever they are printed in debug output | |
41 | * - point-of-acquire tracking, symbolic lookup of function names | |
42 | * - list of all locks held in the system, printout of them | |
43 | * - owner tracking | |
44 | * - detects self-recursing locks and prints out all relevant info | |
45 | * - detects multi-task circular deadlocks and prints out all affected | |
46 | * locks and tasks (and only those tasks) | |
47 | */ | |
48 | struct mutex { | |
49 | /* 1: unlocked, 0: locked, negative: locked, possible waiters */ | |
50 | atomic_t count; | |
51 | spinlock_t wait_lock; | |
52 | struct list_head wait_list; | |
0d66bf6d | 53 | #if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP) |
c6eb3dda | 54 | struct task_struct *owner; |
0d66bf6d | 55 | #endif |
2bd2c92c WL |
56 | #ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
57 | void *spin_mlock; /* Spinner MCS lock */ | |
58 | #endif | |
0d66bf6d | 59 | #ifdef CONFIG_DEBUG_MUTEXES |
6053ee3b IM |
60 | const char *name; |
61 | void *magic; | |
62 | #endif | |
ef5d4707 IM |
63 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
64 | struct lockdep_map dep_map; | |
65 | #endif | |
6053ee3b IM |
66 | }; |
67 | ||
68 | /* | |
69 | * This is the control structure for tasks blocked on mutex, | |
70 | * which resides on the blocked task's kernel stack: | |
71 | */ | |
72 | struct mutex_waiter { | |
73 | struct list_head list; | |
74 | struct task_struct *task; | |
75 | #ifdef CONFIG_DEBUG_MUTEXES | |
6053ee3b | 76 | void *magic; |
6fa3eb70 S |
77 | #ifdef CONFIG_MT_DEBUG_MUTEXES |
78 | struct task_struct *task_wait_on; | |
79 | #endif | |
6053ee3b IM |
80 | #endif |
81 | }; | |
82 | ||
83 | #ifdef CONFIG_DEBUG_MUTEXES | |
84 | # include <linux/mutex-debug.h> | |
85 | #else | |
86 | # define __DEBUG_MUTEX_INITIALIZER(lockname) | |
ef5dc121 RD |
87 | /** |
88 | * mutex_init - initialize the mutex | |
89 | * @mutex: the mutex to be initialized | |
90 | * | |
91 | * Initialize the mutex to unlocked state. | |
92 | * | |
93 | * It is not allowed to initialize an already locked mutex. | |
94 | */ | |
ef5d4707 IM |
95 | # define mutex_init(mutex) \ |
96 | do { \ | |
97 | static struct lock_class_key __key; \ | |
98 | \ | |
99 | __mutex_init((mutex), #mutex, &__key); \ | |
100 | } while (0) | |
4582c0a4 | 101 | static inline void mutex_destroy(struct mutex *lock) {} |
6053ee3b IM |
102 | #endif |
103 | ||
ef5d4707 IM |
104 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
105 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ | |
106 | , .dep_map = { .name = #lockname } | |
107 | #else | |
108 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) | |
109 | #endif | |
110 | ||
6fa3eb70 S |
111 | #ifdef CONFIG_DEBUG_MUTEXES |
112 | #define __MUTEX_NAME_INITIALIZER(lockname) \ | |
113 | , .name = #lockname | |
114 | #else | |
115 | #define __MUTEX_NAME_INITIALIZER(lockname) | |
116 | #endif | |
117 | ||
6053ee3b IM |
118 | #define __MUTEX_INITIALIZER(lockname) \ |
119 | { .count = ATOMIC_INIT(1) \ | |
6cfd76a2 | 120 | , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ |
6053ee3b | 121 | , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ |
ef5d4707 | 122 | __DEBUG_MUTEX_INITIALIZER(lockname) \ |
6fa3eb70 | 123 | __MUTEX_NAME_INITIALIZER(lockname) \ |
ef5d4707 | 124 | __DEP_MAP_MUTEX_INITIALIZER(lockname) } |
6053ee3b IM |
125 | |
126 | #define DEFINE_MUTEX(mutexname) \ | |
127 | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) | |
128 | ||
ef5d4707 IM |
129 | extern void __mutex_init(struct mutex *lock, const char *name, |
130 | struct lock_class_key *key); | |
6053ee3b | 131 | |
45f8bde0 | 132 | /** |
6053ee3b IM |
133 | * mutex_is_locked - is the mutex locked |
134 | * @lock: the mutex to be queried | |
135 | * | |
136 | * Returns 1 if the mutex is locked, 0 if unlocked. | |
137 | */ | |
ec701584 | 138 | static inline int mutex_is_locked(struct mutex *lock) |
6053ee3b IM |
139 | { |
140 | return atomic_read(&lock->count) != 1; | |
141 | } | |
142 | ||
143 | /* | |
144 | * See kernel/mutex.c for detailed documentation of these APIs. | |
145 | * Also see Documentation/mutex-design.txt. | |
146 | */ | |
ef5d4707 IM |
147 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
148 | extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); | |
e4c70a66 | 149 | extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
18d8362d AM |
150 | extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
151 | unsigned int subclass); | |
ad776537 LH |
152 | extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
153 | unsigned int subclass); | |
e4564f79 PZ |
154 | |
155 | #define mutex_lock(lock) mutex_lock_nested(lock, 0) | |
156 | #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) | |
ad776537 | 157 | #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
e4c70a66 PZ |
158 | |
159 | #define mutex_lock_nest_lock(lock, nest_lock) \ | |
160 | do { \ | |
161 | typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ | |
162 | _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ | |
163 | } while (0) | |
164 | ||
ef5d4707 | 165 | #else |
ec701584 HH |
166 | extern void mutex_lock(struct mutex *lock); |
167 | extern int __must_check mutex_lock_interruptible(struct mutex *lock); | |
168 | extern int __must_check mutex_lock_killable(struct mutex *lock); | |
e4564f79 | 169 | |
ef5d4707 | 170 | # define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
d63a5a74 | 171 | # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
ad776537 | 172 | # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
e4c70a66 | 173 | # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
ef5d4707 IM |
174 | #endif |
175 | ||
6053ee3b IM |
176 | /* |
177 | * NOTE: mutex_trylock() follows the spin_trylock() convention, | |
178 | * not the down_trylock() convention! | |
d98d38f2 AV |
179 | * |
180 | * Returns 1 if the mutex has been acquired successfully, and 0 on contention. | |
6053ee3b | 181 | */ |
ec701584 HH |
182 | extern int mutex_trylock(struct mutex *lock); |
183 | extern void mutex_unlock(struct mutex *lock); | |
a511e3f9 | 184 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
b1fca266 | 185 | |
335d7afb GS |
186 | #ifndef CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX |
187 | #define arch_mutex_cpu_relax() cpu_relax() | |
188 | #endif | |
189 | ||
6053ee3b | 190 | #endif |