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