Commit | Line | Data |
---|---|---|
b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
6053ee3b IM |
2 | /* |
3 | * Mutexes: blocking mutual exclusion locks | |
4 | * | |
5 | * started by Ingo Molnar: | |
6 | * | |
7 | * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
8 | * | |
9 | * This file contains the main data structure and API definitions. | |
10 | */ | |
11 | #ifndef __LINUX_MUTEX_H | |
12 | #define __LINUX_MUTEX_H | |
13 | ||
040a0a37 | 14 | #include <asm/current.h> |
6053ee3b IM |
15 | #include <linux/list.h> |
16 | #include <linux/spinlock_types.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 | 22 | |
6baa5c60 NH |
23 | struct ww_acquire_ctx; |
24 | ||
6053ee3b IM |
25 | /* |
26 | * Simple, straightforward mutexes with strict semantics: | |
27 | * | |
28 | * - only one task can hold the mutex at a time | |
29 | * - only the owner can unlock the mutex | |
30 | * - multiple unlocks are not permitted | |
31 | * - recursive locking is not permitted | |
32 | * - a mutex object must be initialized via the API | |
33 | * - a mutex object must not be initialized via memset or copying | |
34 | * - task may not exit with mutex held | |
35 | * - memory areas where held locks reside must not be freed | |
36 | * - held mutexes must not be reinitialized | |
f20fda48 ML |
37 | * - mutexes may not be used in hardware or software interrupt |
38 | * contexts such as tasklets and timers | |
6053ee3b IM |
39 | * |
40 | * These semantics are fully enforced when DEBUG_MUTEXES is | |
41 | * enabled. Furthermore, besides enforcing the above rules, the mutex | |
42 | * debugging code also implements a number of additional features | |
43 | * that make lock debugging easier and faster: | |
44 | * | |
45 | * - uses symbolic names of mutexes, whenever they are printed in debug output | |
46 | * - point-of-acquire tracking, symbolic lookup of function names | |
47 | * - list of all locks held in the system, printout of them | |
48 | * - owner tracking | |
49 | * - detects self-recursing locks and prints out all relevant info | |
50 | * - detects multi-task circular deadlocks and prints out all affected | |
51 | * locks and tasks (and only those tasks) | |
52 | */ | |
53 | struct mutex { | |
3ca0ff57 | 54 | atomic_long_t owner; |
6053ee3b | 55 | spinlock_t wait_lock; |
2bd2c92c | 56 | #ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
90631822 | 57 | struct optimistic_spin_queue osq; /* Spinner MCS lock */ |
2bd2c92c | 58 | #endif |
3ca0ff57 | 59 | struct list_head wait_list; |
0d66bf6d | 60 | #ifdef CONFIG_DEBUG_MUTEXES |
6053ee3b IM |
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 | ||
0cd39f46 PZ |
68 | struct ww_class; |
69 | struct ww_acquire_ctx; | |
70 | ||
71 | struct ww_mutex { | |
72 | struct mutex base; | |
73 | struct ww_acquire_ctx *ctx; | |
74 | #ifdef CONFIG_DEBUG_MUTEXES | |
75 | struct ww_class *ww_class; | |
76 | #endif | |
77 | }; | |
78 | ||
e57d1430 PZ |
79 | /* |
80 | * This is the control structure for tasks blocked on mutex, | |
81 | * which resides on the blocked task's kernel stack: | |
82 | */ | |
83 | struct mutex_waiter { | |
84 | struct list_head list; | |
85 | struct task_struct *task; | |
86 | struct ww_acquire_ctx *ww_ctx; | |
87 | #ifdef CONFIG_DEBUG_MUTEXES | |
88 | void *magic; | |
89 | #endif | |
90 | }; | |
91 | ||
6053ee3b | 92 | #ifdef CONFIG_DEBUG_MUTEXES |
3ca0ff57 PZ |
93 | |
94 | #define __DEBUG_MUTEX_INITIALIZER(lockname) \ | |
95 | , .magic = &lockname | |
96 | ||
97 | extern void mutex_destroy(struct mutex *lock); | |
98 | ||
6053ee3b | 99 | #else |
3ca0ff57 | 100 | |
6053ee3b | 101 | # define __DEBUG_MUTEX_INITIALIZER(lockname) |
3ca0ff57 PZ |
102 | |
103 | static inline void mutex_destroy(struct mutex *lock) {} | |
104 | ||
105 | #endif | |
106 | ||
ef5dc121 RD |
107 | /** |
108 | * mutex_init - initialize the mutex | |
109 | * @mutex: the mutex to be initialized | |
110 | * | |
111 | * Initialize the mutex to unlocked state. | |
112 | * | |
113 | * It is not allowed to initialize an already locked mutex. | |
114 | */ | |
3ca0ff57 PZ |
115 | #define mutex_init(mutex) \ |
116 | do { \ | |
117 | static struct lock_class_key __key; \ | |
118 | \ | |
119 | __mutex_init((mutex), #mutex, &__key); \ | |
ef5d4707 | 120 | } while (0) |
6053ee3b | 121 | |
ef5d4707 | 122 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
de8f5e4f PZ |
123 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ |
124 | , .dep_map = { \ | |
125 | .name = #lockname, \ | |
126 | .wait_type_inner = LD_WAIT_SLEEP, \ | |
127 | } | |
ef5d4707 IM |
128 | #else |
129 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) | |
130 | #endif | |
131 | ||
6053ee3b | 132 | #define __MUTEX_INITIALIZER(lockname) \ |
3ca0ff57 | 133 | { .owner = ATOMIC_LONG_INIT(0) \ |
6cfd76a2 | 134 | , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ |
6053ee3b | 135 | , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ |
ef5d4707 IM |
136 | __DEBUG_MUTEX_INITIALIZER(lockname) \ |
137 | __DEP_MAP_MUTEX_INITIALIZER(lockname) } | |
6053ee3b IM |
138 | |
139 | #define DEFINE_MUTEX(mutexname) \ | |
140 | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) | |
141 | ||
ef5d4707 IM |
142 | extern void __mutex_init(struct mutex *lock, const char *name, |
143 | struct lock_class_key *key); | |
6053ee3b | 144 | |
45f8bde0 | 145 | /** |
6053ee3b IM |
146 | * mutex_is_locked - is the mutex locked |
147 | * @lock: the mutex to be queried | |
148 | * | |
db076bef | 149 | * Returns true if the mutex is locked, false if unlocked. |
6053ee3b | 150 | */ |
5f35d5a6 | 151 | extern bool mutex_is_locked(struct mutex *lock); |
6053ee3b IM |
152 | |
153 | /* | |
67a6de49 | 154 | * See kernel/locking/mutex.c for detailed documentation of these APIs. |
387b1468 | 155 | * Also see Documentation/locking/mutex-design.rst. |
6053ee3b | 156 | */ |
ef5d4707 IM |
157 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
158 | extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); | |
e4c70a66 | 159 | extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
040a0a37 | 160 | |
18d8362d AM |
161 | extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
162 | unsigned int subclass); | |
ad776537 LH |
163 | extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
164 | unsigned int subclass); | |
1460cb65 | 165 | extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass); |
e4564f79 PZ |
166 | |
167 | #define mutex_lock(lock) mutex_lock_nested(lock, 0) | |
168 | #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) | |
ad776537 | 169 | #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
1460cb65 | 170 | #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0) |
e4c70a66 PZ |
171 | |
172 | #define mutex_lock_nest_lock(lock, nest_lock) \ | |
173 | do { \ | |
040a0a37 | 174 | typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ |
e4c70a66 PZ |
175 | _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ |
176 | } while (0) | |
177 | ||
ef5d4707 | 178 | #else |
ec701584 HH |
179 | extern void mutex_lock(struct mutex *lock); |
180 | extern int __must_check mutex_lock_interruptible(struct mutex *lock); | |
181 | extern int __must_check mutex_lock_killable(struct mutex *lock); | |
1460cb65 | 182 | extern void mutex_lock_io(struct mutex *lock); |
e4564f79 | 183 | |
ef5d4707 | 184 | # define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
d63a5a74 | 185 | # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
ad776537 | 186 | # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
e4c70a66 | 187 | # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
f21860ba | 188 | # define mutex_lock_io_nested(lock, subclass) mutex_lock(lock) |
ef5d4707 IM |
189 | #endif |
190 | ||
6053ee3b IM |
191 | /* |
192 | * NOTE: mutex_trylock() follows the spin_trylock() convention, | |
193 | * not the down_trylock() convention! | |
d98d38f2 AV |
194 | * |
195 | * Returns 1 if the mutex has been acquired successfully, and 0 on contention. | |
6053ee3b | 196 | */ |
ec701584 HH |
197 | extern int mutex_trylock(struct mutex *lock); |
198 | extern void mutex_unlock(struct mutex *lock); | |
040a0a37 | 199 | |
a511e3f9 | 200 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
b1fca266 | 201 | |
e7224674 | 202 | #endif /* __LINUX_MUTEX_H */ |