1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Mutexes: blocking mutual exclusion locks
5 * started by Ingo Molnar:
7 * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * This file contains the main data structure and API definitions.
11 #ifndef __LINUX_MUTEX_H
12 #define __LINUX_MUTEX_H
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>
25 #ifdef CONFIG_DEBUG_LOCK_ALLOC
26 # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
29 .wait_type_inner = LD_WAIT_SLEEP, \
32 # define __DEP_MAP_MUTEX_INITIALIZER(lockname)
35 #ifdef CONFIG_DEBUG_MUTEXES
37 # define __DEBUG_MUTEX_INITIALIZER(lockname) \
40 extern void mutex_destroy(struct mutex *lock);
44 # define __DEBUG_MUTEX_INITIALIZER(lockname)
46 static inline void mutex_destroy(struct mutex *lock) {}
50 #ifndef CONFIG_PREEMPT_RT
52 * mutex_init - initialize the mutex
53 * @mutex: the mutex to be initialized
55 * Initialize the mutex to unlocked state.
57 * It is not allowed to initialize an already locked mutex.
59 #define mutex_init(mutex) \
61 static struct lock_class_key __key; \
63 __mutex_init((mutex), #mutex, &__key); \
66 #define __MUTEX_INITIALIZER(lockname) \
67 { .owner = ATOMIC_LONG_INIT(0) \
68 , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
69 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
70 __DEBUG_MUTEX_INITIALIZER(lockname) \
71 __DEP_MAP_MUTEX_INITIALIZER(lockname) }
73 #define DEFINE_MUTEX(mutexname) \
74 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
76 extern void __mutex_init(struct mutex *lock, const char *name,
77 struct lock_class_key *key);
80 * mutex_is_locked - is the mutex locked
81 * @lock: the mutex to be queried
83 * Returns true if the mutex is locked, false if unlocked.
85 extern bool mutex_is_locked(struct mutex *lock);
87 #else /* !CONFIG_PREEMPT_RT */
89 * Preempt-RT variant based on rtmutexes.
92 #define __MUTEX_INITIALIZER(mutexname) \
94 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \
95 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \
98 #define DEFINE_MUTEX(mutexname) \
99 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
101 extern void __mutex_rt_init(struct mutex *lock, const char *name,
102 struct lock_class_key *key);
104 #define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex)
106 #define __mutex_init(mutex, name, key) \
108 rt_mutex_base_init(&(mutex)->rtmutex); \
109 __mutex_rt_init((mutex), name, key); \
112 #define mutex_init(mutex) \
114 static struct lock_class_key __key; \
116 __mutex_init((mutex), #mutex, &__key); \
118 #endif /* CONFIG_PREEMPT_RT */
121 * See kernel/locking/mutex.c for detailed documentation of these APIs.
122 * Also see Documentation/locking/mutex-design.rst.
124 #ifdef CONFIG_DEBUG_LOCK_ALLOC
125 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
126 extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
128 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
129 unsigned int subclass);
130 extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
131 unsigned int subclass);
132 extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
134 #define mutex_lock(lock) mutex_lock_nested(lock, 0)
135 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
136 #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
137 #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
139 #define mutex_lock_nest_lock(lock, nest_lock) \
141 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
142 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
146 extern void mutex_lock(struct mutex *lock);
147 extern int __must_check mutex_lock_interruptible(struct mutex *lock);
148 extern int __must_check mutex_lock_killable(struct mutex *lock);
149 extern void mutex_lock_io(struct mutex *lock);
151 # define mutex_lock_nested(lock, subclass) mutex_lock(lock)
152 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
153 # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
154 # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
155 # define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
159 * NOTE: mutex_trylock() follows the spin_trylock() convention,
160 * not the down_trylock() convention!
162 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
164 extern int mutex_trylock(struct mutex *lock);
165 extern void mutex_unlock(struct mutex *lock);
167 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
169 DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
170 DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
171 DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
173 #endif /* __LINUX_MUTEX_H */