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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> | |
a8b9ee73 | 17 | #include <linux/linkage.h> |
ef5d4707 | 18 | #include <linux/lockdep.h> |
60063497 | 19 | #include <linux/atomic.h> |
083986e8 | 20 | #include <asm/processor.h> |
90631822 | 21 | #include <linux/osq_lock.h> |
3ca0ff57 | 22 | #include <linux/debug_locks.h> |
6053ee3b | 23 | |
6baa5c60 NH |
24 | struct ww_acquire_ctx; |
25 | ||
6053ee3b IM |
26 | /* |
27 | * Simple, straightforward mutexes with strict semantics: | |
28 | * | |
29 | * - only one task can hold the mutex at a time | |
30 | * - only the owner can unlock the mutex | |
31 | * - multiple unlocks are not permitted | |
32 | * - recursive locking is not permitted | |
33 | * - a mutex object must be initialized via the API | |
34 | * - a mutex object must not be initialized via memset or copying | |
35 | * - task may not exit with mutex held | |
36 | * - memory areas where held locks reside must not be freed | |
37 | * - held mutexes must not be reinitialized | |
f20fda48 ML |
38 | * - mutexes may not be used in hardware or software interrupt |
39 | * contexts such as tasklets and timers | |
6053ee3b IM |
40 | * |
41 | * These semantics are fully enforced when DEBUG_MUTEXES is | |
42 | * enabled. Furthermore, besides enforcing the above rules, the mutex | |
43 | * debugging code also implements a number of additional features | |
44 | * that make lock debugging easier and faster: | |
45 | * | |
46 | * - uses symbolic names of mutexes, whenever they are printed in debug output | |
47 | * - point-of-acquire tracking, symbolic lookup of function names | |
48 | * - list of all locks held in the system, printout of them | |
49 | * - owner tracking | |
50 | * - detects self-recursing locks and prints out all relevant info | |
51 | * - detects multi-task circular deadlocks and prints out all affected | |
52 | * locks and tasks (and only those tasks) | |
53 | */ | |
54 | struct mutex { | |
3ca0ff57 | 55 | atomic_long_t owner; |
6053ee3b | 56 | spinlock_t wait_lock; |
2bd2c92c | 57 | #ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
90631822 | 58 | struct optimistic_spin_queue osq; /* Spinner MCS lock */ |
2bd2c92c | 59 | #endif |
3ca0ff57 | 60 | struct list_head wait_list; |
0d66bf6d | 61 | #ifdef CONFIG_DEBUG_MUTEXES |
6053ee3b IM |
62 | void *magic; |
63 | #endif | |
ef5d4707 IM |
64 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
65 | struct lockdep_map dep_map; | |
66 | #endif | |
6053ee3b IM |
67 | }; |
68 | ||
3ca0ff57 PZ |
69 | static inline struct task_struct *__mutex_owner(struct mutex *lock) |
70 | { | |
e274795e | 71 | return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x07); |
3ca0ff57 PZ |
72 | } |
73 | ||
6053ee3b IM |
74 | /* |
75 | * This is the control structure for tasks blocked on mutex, | |
76 | * which resides on the blocked task's kernel stack: | |
77 | */ | |
78 | struct mutex_waiter { | |
79 | struct list_head list; | |
80 | struct task_struct *task; | |
6baa5c60 | 81 | struct ww_acquire_ctx *ww_ctx; |
6053ee3b | 82 | #ifdef CONFIG_DEBUG_MUTEXES |
6053ee3b IM |
83 | void *magic; |
84 | #endif | |
85 | }; | |
86 | ||
87 | #ifdef CONFIG_DEBUG_MUTEXES | |
3ca0ff57 PZ |
88 | |
89 | #define __DEBUG_MUTEX_INITIALIZER(lockname) \ | |
90 | , .magic = &lockname | |
91 | ||
92 | extern void mutex_destroy(struct mutex *lock); | |
93 | ||
6053ee3b | 94 | #else |
3ca0ff57 | 95 | |
6053ee3b | 96 | # define __DEBUG_MUTEX_INITIALIZER(lockname) |
3ca0ff57 PZ |
97 | |
98 | static inline void mutex_destroy(struct mutex *lock) {} | |
99 | ||
100 | #endif | |
101 | ||
ef5dc121 RD |
102 | /** |
103 | * mutex_init - initialize the mutex | |
104 | * @mutex: the mutex to be initialized | |
105 | * | |
106 | * Initialize the mutex to unlocked state. | |
107 | * | |
108 | * It is not allowed to initialize an already locked mutex. | |
109 | */ | |
3ca0ff57 PZ |
110 | #define mutex_init(mutex) \ |
111 | do { \ | |
112 | static struct lock_class_key __key; \ | |
113 | \ | |
114 | __mutex_init((mutex), #mutex, &__key); \ | |
ef5d4707 | 115 | } while (0) |
6053ee3b | 116 | |
ef5d4707 IM |
117 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
118 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ | |
119 | , .dep_map = { .name = #lockname } | |
120 | #else | |
121 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) | |
122 | #endif | |
123 | ||
6053ee3b | 124 | #define __MUTEX_INITIALIZER(lockname) \ |
3ca0ff57 | 125 | { .owner = ATOMIC_LONG_INIT(0) \ |
6cfd76a2 | 126 | , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ |
6053ee3b | 127 | , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ |
ef5d4707 IM |
128 | __DEBUG_MUTEX_INITIALIZER(lockname) \ |
129 | __DEP_MAP_MUTEX_INITIALIZER(lockname) } | |
6053ee3b IM |
130 | |
131 | #define DEFINE_MUTEX(mutexname) \ | |
132 | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) | |
133 | ||
ef5d4707 IM |
134 | extern void __mutex_init(struct mutex *lock, const char *name, |
135 | struct lock_class_key *key); | |
6053ee3b | 136 | |
45f8bde0 | 137 | /** |
6053ee3b IM |
138 | * mutex_is_locked - is the mutex locked |
139 | * @lock: the mutex to be queried | |
140 | * | |
141 | * Returns 1 if the mutex is locked, 0 if unlocked. | |
142 | */ | |
ec701584 | 143 | static inline int mutex_is_locked(struct mutex *lock) |
6053ee3b | 144 | { |
3ca0ff57 PZ |
145 | /* |
146 | * XXX think about spin_is_locked | |
147 | */ | |
148 | return __mutex_owner(lock) != NULL; | |
6053ee3b IM |
149 | } |
150 | ||
151 | /* | |
67a6de49 | 152 | * See kernel/locking/mutex.c for detailed documentation of these APIs. |
214e0aed | 153 | * Also see Documentation/locking/mutex-design.txt. |
6053ee3b | 154 | */ |
ef5d4707 IM |
155 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
156 | extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); | |
e4c70a66 | 157 | extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
040a0a37 | 158 | |
18d8362d AM |
159 | extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
160 | unsigned int subclass); | |
ad776537 LH |
161 | extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
162 | unsigned int subclass); | |
1460cb65 | 163 | extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass); |
e4564f79 PZ |
164 | |
165 | #define mutex_lock(lock) mutex_lock_nested(lock, 0) | |
166 | #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) | |
ad776537 | 167 | #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
1460cb65 | 168 | #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0) |
e4c70a66 PZ |
169 | |
170 | #define mutex_lock_nest_lock(lock, nest_lock) \ | |
171 | do { \ | |
040a0a37 | 172 | typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ |
e4c70a66 PZ |
173 | _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ |
174 | } while (0) | |
175 | ||
ef5d4707 | 176 | #else |
ec701584 HH |
177 | extern void mutex_lock(struct mutex *lock); |
178 | extern int __must_check mutex_lock_interruptible(struct mutex *lock); | |
179 | extern int __must_check mutex_lock_killable(struct mutex *lock); | |
1460cb65 | 180 | extern void mutex_lock_io(struct mutex *lock); |
e4564f79 | 181 | |
ef5d4707 | 182 | # define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
d63a5a74 | 183 | # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
ad776537 | 184 | # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
e4c70a66 | 185 | # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
f21860ba | 186 | # define mutex_lock_io_nested(lock, subclass) mutex_lock(lock) |
ef5d4707 IM |
187 | #endif |
188 | ||
6053ee3b IM |
189 | /* |
190 | * NOTE: mutex_trylock() follows the spin_trylock() convention, | |
191 | * not the down_trylock() convention! | |
d98d38f2 AV |
192 | * |
193 | * Returns 1 if the mutex has been acquired successfully, and 0 on contention. | |
6053ee3b | 194 | */ |
ec701584 HH |
195 | extern int mutex_trylock(struct mutex *lock); |
196 | extern void mutex_unlock(struct mutex *lock); | |
040a0a37 | 197 | |
a511e3f9 | 198 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
b1fca266 | 199 | |
0f5225b0 PZ |
200 | /* |
201 | * These values are chosen such that FAIL and SUCCESS match the | |
202 | * values of the regular mutex_trylock(). | |
203 | */ | |
204 | enum mutex_trylock_recursive_enum { | |
205 | MUTEX_TRYLOCK_FAILED = 0, | |
206 | MUTEX_TRYLOCK_SUCCESS = 1, | |
207 | MUTEX_TRYLOCK_RECURSIVE, | |
208 | }; | |
209 | ||
210 | /** | |
211 | * mutex_trylock_recursive - trylock variant that allows recursive locking | |
212 | * @lock: mutex to be locked | |
213 | * | |
214 | * This function should not be used, _ever_. It is purely for hysterical GEM | |
215 | * raisins, and once those are gone this will be removed. | |
216 | * | |
217 | * Returns: | |
7b4ff1ad MCC |
218 | * - MUTEX_TRYLOCK_FAILED - trylock failed, |
219 | * - MUTEX_TRYLOCK_SUCCESS - lock acquired, | |
220 | * - MUTEX_TRYLOCK_RECURSIVE - we already owned the lock. | |
0f5225b0 | 221 | */ |
43496d35 | 222 | static inline /* __deprecated */ __must_check enum mutex_trylock_recursive_enum |
0f5225b0 PZ |
223 | mutex_trylock_recursive(struct mutex *lock) |
224 | { | |
225 | if (unlikely(__mutex_owner(lock) == current)) | |
226 | return MUTEX_TRYLOCK_RECURSIVE; | |
227 | ||
228 | return mutex_trylock(lock); | |
229 | } | |
230 | ||
e7224674 | 231 | #endif /* __LINUX_MUTEX_H */ |