Root/
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 <asm/current.h> |
14 | #include <linux/list.h> |
15 | #include <linux/spinlock_types.h> |
16 | #include <linux/linkage.h> |
17 | #include <linux/lockdep.h> |
18 | #include <linux/atomic.h> |
19 | #include <asm/processor.h> |
20 | |
21 | /* |
22 | * Simple, straightforward mutexes with strict semantics: |
23 | * |
24 | * - only one task can hold the mutex at a time |
25 | * - only the owner can unlock the mutex |
26 | * - multiple unlocks are not permitted |
27 | * - recursive locking is not permitted |
28 | * - a mutex object must be initialized via the API |
29 | * - a mutex object must not be initialized via memset or copying |
30 | * - task may not exit with mutex held |
31 | * - memory areas where held locks reside must not be freed |
32 | * - held mutexes must not be reinitialized |
33 | * - mutexes may not be used in hardware or software interrupt |
34 | * contexts such as tasklets and timers |
35 | * |
36 | * These semantics are fully enforced when DEBUG_MUTEXES is |
37 | * enabled. Furthermore, besides enforcing the above rules, the mutex |
38 | * debugging code also implements a number of additional features |
39 | * that make lock debugging easier and faster: |
40 | * |
41 | * - uses symbolic names of mutexes, whenever they are printed in debug output |
42 | * - point-of-acquire tracking, symbolic lookup of function names |
43 | * - list of all locks held in the system, printout of them |
44 | * - owner tracking |
45 | * - detects self-recursing locks and prints out all relevant info |
46 | * - detects multi-task circular deadlocks and prints out all affected |
47 | * locks and tasks (and only those tasks) |
48 | */ |
49 | struct mutex { |
50 | /* 1: unlocked, 0: locked, negative: locked, possible waiters */ |
51 | atomic_t count; |
52 | spinlock_t wait_lock; |
53 | struct list_head wait_list; |
54 | #if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP) |
55 | struct task_struct *owner; |
56 | #endif |
57 | #ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
58 | void *spin_mlock; /* Spinner MCS lock */ |
59 | #endif |
60 | #ifdef CONFIG_DEBUG_MUTEXES |
61 | const char *name; |
62 | void *magic; |
63 | #endif |
64 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
65 | struct lockdep_map dep_map; |
66 | #endif |
67 | }; |
68 | |
69 | /* |
70 | * This is the control structure for tasks blocked on mutex, |
71 | * which resides on the blocked task's kernel stack: |
72 | */ |
73 | struct mutex_waiter { |
74 | struct list_head list; |
75 | struct task_struct *task; |
76 | #ifdef CONFIG_DEBUG_MUTEXES |
77 | void *magic; |
78 | #endif |
79 | }; |
80 | |
81 | #ifdef CONFIG_DEBUG_MUTEXES |
82 | # include <linux/mutex-debug.h> |
83 | #else |
84 | # define __DEBUG_MUTEX_INITIALIZER(lockname) |
85 | /** |
86 | * mutex_init - initialize the mutex |
87 | * @mutex: the mutex to be initialized |
88 | * |
89 | * Initialize the mutex to unlocked state. |
90 | * |
91 | * It is not allowed to initialize an already locked mutex. |
92 | */ |
93 | # define mutex_init(mutex) \ |
94 | do { \ |
95 | static struct lock_class_key __key; \ |
96 | \ |
97 | __mutex_init((mutex), #mutex, &__key); \ |
98 | } while (0) |
99 | static inline void mutex_destroy(struct mutex *lock) {} |
100 | #endif |
101 | |
102 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
103 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ |
104 | , .dep_map = { .name = #lockname } |
105 | #else |
106 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) |
107 | #endif |
108 | |
109 | #define __MUTEX_INITIALIZER(lockname) \ |
110 | { .count = ATOMIC_INIT(1) \ |
111 | , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ |
112 | , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ |
113 | __DEBUG_MUTEX_INITIALIZER(lockname) \ |
114 | __DEP_MAP_MUTEX_INITIALIZER(lockname) } |
115 | |
116 | #define DEFINE_MUTEX(mutexname) \ |
117 | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) |
118 | |
119 | extern void __mutex_init(struct mutex *lock, const char *name, |
120 | struct lock_class_key *key); |
121 | |
122 | /** |
123 | * mutex_is_locked - is the mutex locked |
124 | * @lock: the mutex to be queried |
125 | * |
126 | * Returns 1 if the mutex is locked, 0 if unlocked. |
127 | */ |
128 | static inline int mutex_is_locked(struct mutex *lock) |
129 | { |
130 | return atomic_read(&lock->count) != 1; |
131 | } |
132 | |
133 | /* |
134 | * See kernel/locking/mutex.c for detailed documentation of these APIs. |
135 | * Also see Documentation/mutex-design.txt. |
136 | */ |
137 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
138 | extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); |
139 | extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
140 | |
141 | extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
142 | unsigned int subclass); |
143 | extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
144 | unsigned int subclass); |
145 | |
146 | #define mutex_lock(lock) mutex_lock_nested(lock, 0) |
147 | #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) |
148 | #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
149 | |
150 | #define mutex_lock_nest_lock(lock, nest_lock) \ |
151 | do { \ |
152 | typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ |
153 | _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ |
154 | } while (0) |
155 | |
156 | #else |
157 | extern void mutex_lock(struct mutex *lock); |
158 | extern int __must_check mutex_lock_interruptible(struct mutex *lock); |
159 | extern int __must_check mutex_lock_killable(struct mutex *lock); |
160 | |
161 | # define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
162 | # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
163 | # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
164 | # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
165 | #endif |
166 | |
167 | /* |
168 | * NOTE: mutex_trylock() follows the spin_trylock() convention, |
169 | * not the down_trylock() convention! |
170 | * |
171 | * Returns 1 if the mutex has been acquired successfully, and 0 on contention. |
172 | */ |
173 | extern int mutex_trylock(struct mutex *lock); |
174 | extern void mutex_unlock(struct mutex *lock); |
175 | |
176 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
177 | |
178 | #ifndef arch_mutex_cpu_relax |
179 | # define arch_mutex_cpu_relax() cpu_relax() |
180 | #endif |
181 | |
182 | #endif |
183 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9