1 | /* SPDX-License-Identifier: GPL-2.0 */ |
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 | |
14 | #include <asm/current.h> |
15 | #include <linux/list.h> |
16 | #include <linux/spinlock_types.h> |
17 | #include <linux/lockdep.h> |
18 | #include <linux/atomic.h> |
19 | #include <asm/processor.h> |
20 | #include <linux/osq_lock.h> |
21 | #include <linux/debug_locks.h> |
22 | #include <linux/cleanup.h> |
23 | |
24 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
25 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ |
26 | , .dep_map = { \ |
27 | .name = #lockname, \ |
28 | .wait_type_inner = LD_WAIT_SLEEP, \ |
29 | } |
30 | #else |
31 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) |
32 | #endif |
33 | |
34 | #ifndef CONFIG_PREEMPT_RT |
35 | |
36 | /* |
37 | * Simple, straightforward mutexes with strict semantics: |
38 | * |
39 | * - only one task can hold the mutex at a time |
40 | * - only the owner can unlock the mutex |
41 | * - multiple unlocks are not permitted |
42 | * - recursive locking is not permitted |
43 | * - a mutex object must be initialized via the API |
44 | * - a mutex object must not be initialized via memset or copying |
45 | * - task may not exit with mutex held |
46 | * - memory areas where held locks reside must not be freed |
47 | * - held mutexes must not be reinitialized |
48 | * - mutexes may not be used in hardware or software interrupt |
49 | * contexts such as tasklets and timers |
50 | * |
51 | * These semantics are fully enforced when DEBUG_MUTEXES is |
52 | * enabled. Furthermore, besides enforcing the above rules, the mutex |
53 | * debugging code also implements a number of additional features |
54 | * that make lock debugging easier and faster: |
55 | * |
56 | * - uses symbolic names of mutexes, whenever they are printed in debug output |
57 | * - point-of-acquire tracking, symbolic lookup of function names |
58 | * - list of all locks held in the system, printout of them |
59 | * - owner tracking |
60 | * - detects self-recursing locks and prints out all relevant info |
61 | * - detects multi-task circular deadlocks and prints out all affected |
62 | * locks and tasks (and only those tasks) |
63 | */ |
64 | struct mutex { |
65 | atomic_long_t owner; |
66 | raw_spinlock_t wait_lock; |
67 | #ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
68 | struct optimistic_spin_queue osq; /* Spinner MCS lock */ |
69 | #endif |
70 | struct list_head wait_list; |
71 | #ifdef CONFIG_DEBUG_MUTEXES |
72 | void *magic; |
73 | #endif |
74 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
75 | struct lockdep_map dep_map; |
76 | #endif |
77 | }; |
78 | |
79 | #ifdef CONFIG_DEBUG_MUTEXES |
80 | |
81 | #define __DEBUG_MUTEX_INITIALIZER(lockname) \ |
82 | , .magic = &lockname |
83 | |
84 | extern void mutex_destroy(struct mutex *lock); |
85 | |
86 | #else |
87 | |
88 | # define __DEBUG_MUTEX_INITIALIZER(lockname) |
89 | |
90 | static inline void mutex_destroy(struct mutex *lock) {} |
91 | |
92 | #endif |
93 | |
94 | /** |
95 | * mutex_init - initialize the mutex |
96 | * @mutex: the mutex to be initialized |
97 | * |
98 | * Initialize the mutex to unlocked state. |
99 | * |
100 | * It is not allowed to initialize an already locked mutex. |
101 | */ |
102 | #define mutex_init(mutex) \ |
103 | do { \ |
104 | static struct lock_class_key __key; \ |
105 | \ |
106 | __mutex_init((mutex), #mutex, &__key); \ |
107 | } while (0) |
108 | |
109 | #define __MUTEX_INITIALIZER(lockname) \ |
110 | { .owner = ATOMIC_LONG_INIT(0) \ |
111 | , .wait_lock = __RAW_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 true if the mutex is locked, false if unlocked. |
127 | */ |
128 | extern bool mutex_is_locked(struct mutex *lock); |
129 | |
130 | #else /* !CONFIG_PREEMPT_RT */ |
131 | /* |
132 | * Preempt-RT variant based on rtmutexes. |
133 | */ |
134 | #include <linux/rtmutex.h> |
135 | |
136 | struct mutex { |
137 | struct rt_mutex_base rtmutex; |
138 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
139 | struct lockdep_map dep_map; |
140 | #endif |
141 | }; |
142 | |
143 | #define __MUTEX_INITIALIZER(mutexname) \ |
144 | { \ |
145 | .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \ |
146 | __DEP_MAP_MUTEX_INITIALIZER(mutexname) \ |
147 | } |
148 | |
149 | #define DEFINE_MUTEX(mutexname) \ |
150 | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) |
151 | |
152 | extern void __mutex_rt_init(struct mutex *lock, const char *name, |
153 | struct lock_class_key *key); |
154 | extern int mutex_trylock(struct mutex *lock); |
155 | |
156 | static inline void mutex_destroy(struct mutex *lock) { } |
157 | |
158 | #define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex) |
159 | |
160 | #define __mutex_init(mutex, name, key) \ |
161 | do { \ |
162 | rt_mutex_base_init(&(mutex)->rtmutex); \ |
163 | __mutex_rt_init((mutex), name, key); \ |
164 | } while (0) |
165 | |
166 | #define mutex_init(mutex) \ |
167 | do { \ |
168 | static struct lock_class_key __key; \ |
169 | \ |
170 | __mutex_init((mutex), #mutex, &__key); \ |
171 | } while (0) |
172 | #endif /* CONFIG_PREEMPT_RT */ |
173 | |
174 | /* |
175 | * See kernel/locking/mutex.c for detailed documentation of these APIs. |
176 | * Also see Documentation/locking/mutex-design.rst. |
177 | */ |
178 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
179 | extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); |
180 | extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
181 | |
182 | extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
183 | unsigned int subclass); |
184 | extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
185 | unsigned int subclass); |
186 | extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass); |
187 | |
188 | #define mutex_lock(lock) mutex_lock_nested(lock, 0) |
189 | #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) |
190 | #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
191 | #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0) |
192 | |
193 | #define mutex_lock_nest_lock(lock, nest_lock) \ |
194 | do { \ |
195 | typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ |
196 | _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ |
197 | } while (0) |
198 | |
199 | #else |
200 | extern void mutex_lock(struct mutex *lock); |
201 | extern int __must_check mutex_lock_interruptible(struct mutex *lock); |
202 | extern int __must_check mutex_lock_killable(struct mutex *lock); |
203 | extern void mutex_lock_io(struct mutex *lock); |
204 | |
205 | # define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
206 | # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
207 | # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
208 | # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
209 | # define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock) |
210 | #endif |
211 | |
212 | /* |
213 | * NOTE: mutex_trylock() follows the spin_trylock() convention, |
214 | * not the down_trylock() convention! |
215 | * |
216 | * Returns 1 if the mutex has been acquired successfully, and 0 on contention. |
217 | */ |
218 | extern int mutex_trylock(struct mutex *lock); |
219 | extern void mutex_unlock(struct mutex *lock); |
220 | |
221 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
222 | |
223 | DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T)) |
224 | DEFINE_FREE(mutex, struct mutex *, if (_T) mutex_unlock(_T)) |
225 | |
226 | #endif /* __LINUX_MUTEX_H */ |
227 | |