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 #include <linux/mutex_types.h>
24
25 struct device;
26
27 #ifdef CONFIG_DEBUG_LOCK_ALLOC
28 # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
29 , .dep_map = { \
30 .name = #lockname, \
31 .wait_type_inner = LD_WAIT_SLEEP, \
32 }
33 #else
34 # define __DEP_MAP_MUTEX_INITIALIZER(lockname)
35 #endif
36
37 #ifdef CONFIG_DEBUG_MUTEXES
38
39 # define __DEBUG_MUTEX_INITIALIZER(lockname) \
40 , .magic = &lockname
41
42 extern void mutex_destroy(struct mutex *lock);
43
44 #else
45
46 # define __DEBUG_MUTEX_INITIALIZER(lockname)
47
mutex_destroy(struct mutex * lock)48 static inline void mutex_destroy(struct mutex *lock) {}
49
50 #endif
51
52 /**
53 * mutex_init - initialize the mutex
54 * @mutex: the mutex to be initialized
55 *
56 * Initialize the mutex to unlocked state.
57 *
58 * It is not allowed to initialize an already locked mutex.
59 */
60 #define mutex_init(mutex) \
61 do { \
62 static struct lock_class_key __key; \
63 \
64 __mutex_init((mutex), #mutex, &__key); \
65 } while (0)
66
67 /**
68 * mutex_init_with_key - initialize a mutex with a given lockdep key
69 * @mutex: the mutex to be initialized
70 * @key: the lockdep key to be associated with the mutex
71 *
72 * Initialize the mutex to the unlocked state.
73 *
74 * It is not allowed to initialize an already locked mutex.
75 */
76 #define mutex_init_with_key(mutex, key) __mutex_init((mutex), #mutex, (key))
77
78 #ifndef CONFIG_PREEMPT_RT
79 #define __MUTEX_INITIALIZER(lockname) \
80 { .owner = ATOMIC_LONG_INIT(0) \
81 , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
82 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
83 __DEBUG_MUTEX_INITIALIZER(lockname) \
84 __DEP_MAP_MUTEX_INITIALIZER(lockname) }
85
86 #define DEFINE_MUTEX(mutexname) \
87 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
88
89 extern void __mutex_init(struct mutex *lock, const char *name,
90 struct lock_class_key *key);
91
92 /**
93 * mutex_is_locked - is the mutex locked
94 * @lock: the mutex to be queried
95 *
96 * Returns true if the mutex is locked, false if unlocked.
97 */
98 extern bool mutex_is_locked(struct mutex *lock);
99
100 #else /* !CONFIG_PREEMPT_RT */
101 /*
102 * Preempt-RT variant based on rtmutexes.
103 */
104
105 #define __MUTEX_INITIALIZER(mutexname) \
106 { \
107 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \
108 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \
109 }
110
111 #define DEFINE_MUTEX(mutexname) \
112 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
113
114 extern void __mutex_rt_init(struct mutex *lock, const char *name,
115 struct lock_class_key *key);
116
117 #define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex)
118
119 #define __mutex_init(mutex, name, key) \
120 do { \
121 rt_mutex_base_init(&(mutex)->rtmutex); \
122 __mutex_rt_init((mutex), name, key); \
123 } while (0)
124
125 #endif /* CONFIG_PREEMPT_RT */
126
127 #ifdef CONFIG_DEBUG_MUTEXES
128
129 int __must_check __devm_mutex_init(struct device *dev, struct mutex *lock);
130
131 #else
132
__devm_mutex_init(struct device * dev,struct mutex * lock)133 static inline int __must_check __devm_mutex_init(struct device *dev, struct mutex *lock)
134 {
135 /*
136 * When CONFIG_DEBUG_MUTEXES is off mutex_destroy() is just a nop so
137 * no really need to register it in the devm subsystem.
138 */
139 return 0;
140 }
141
142 #endif
143
144 #define __mutex_init_ret(mutex) \
145 ({ \
146 typeof(mutex) mutex_ = (mutex); \
147 \
148 mutex_init(mutex_); \
149 mutex_; \
150 })
151
152 #define devm_mutex_init(dev, mutex) \
153 __devm_mutex_init(dev, __mutex_init_ret(mutex))
154
155 /*
156 * See kernel/locking/mutex.c for detailed documentation of these APIs.
157 * Also see Documentation/locking/mutex-design.rst.
158 */
159 #ifdef CONFIG_DEBUG_LOCK_ALLOC
160 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
161 extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
162 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
163 unsigned int subclass);
164 extern int __must_check _mutex_lock_killable(struct mutex *lock,
165 unsigned int subclass, struct lockdep_map *nest_lock);
166 extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
167
168 #define mutex_lock(lock) mutex_lock_nested(lock, 0)
169 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
170 #define mutex_lock_killable(lock) _mutex_lock_killable(lock, 0, NULL)
171 #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
172
173 #define mutex_lock_nest_lock(lock, nest_lock) \
174 do { \
175 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
176 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
177 } while (0)
178
179 #define mutex_lock_killable_nest_lock(lock, nest_lock) \
180 ( \
181 typecheck(struct lockdep_map *, &(nest_lock)->dep_map), \
182 _mutex_lock_killable(lock, 0, &(nest_lock)->dep_map) \
183 )
184
185 #define mutex_lock_killable_nested(lock, subclass) \
186 _mutex_lock_killable(lock, subclass, NULL)
187
188 #else
189 extern void mutex_lock(struct mutex *lock);
190 extern int __must_check mutex_lock_interruptible(struct mutex *lock);
191 extern int __must_check mutex_lock_killable(struct mutex *lock);
192 extern void mutex_lock_io(struct mutex *lock);
193
194 # define mutex_lock_nested(lock, subclass) mutex_lock(lock)
195 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
196 # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
197 # define mutex_lock_killable_nest_lock(lock, nest_lock) mutex_lock_killable(lock)
198 # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
199 # define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
200 #endif
201
202 /*
203 * NOTE: mutex_trylock() follows the spin_trylock() convention,
204 * not the down_trylock() convention!
205 *
206 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
207 */
208
209 #ifdef CONFIG_DEBUG_LOCK_ALLOC
210 extern int _mutex_trylock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
211
212 #define mutex_trylock_nest_lock(lock, nest_lock) \
213 ( \
214 typecheck(struct lockdep_map *, &(nest_lock)->dep_map), \
215 _mutex_trylock_nest_lock(lock, &(nest_lock)->dep_map) \
216 )
217
218 #define mutex_trylock(lock) _mutex_trylock_nest_lock(lock, NULL)
219 #else
220 extern int mutex_trylock(struct mutex *lock);
221 #define mutex_trylock_nest_lock(lock, nest_lock) mutex_trylock(lock)
222 #endif
223
224 extern void mutex_unlock(struct mutex *lock);
225
226 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
227
228 DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
229 DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
230 DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T), _RET == 0)
231
232 extern unsigned long mutex_get_owner(struct mutex *lock);
233
234 #endif /* __LINUX_MUTEX_H */
235