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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#ifdef CONFIG_DEBUG_LOCK_ALLOC
26# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
27 , .dep_map = { \
28 .name = #lockname, \
29 .wait_type_inner = LD_WAIT_SLEEP, \
30 }
31#else
32# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
33#endif
34
35#ifndef CONFIG_PREEMPT_RT
36
37#ifdef CONFIG_DEBUG_MUTEXES
38
39#define __DEBUG_MUTEX_INITIALIZER(lockname) \
40 , .magic = &lockname
41
42extern void mutex_destroy(struct mutex *lock);
43
44#else
45
46# define __DEBUG_MUTEX_INITIALIZER(lockname)
47
48static 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) \
61do { \
62 static struct lock_class_key __key; \
63 \
64 __mutex_init((mutex), #mutex, &__key); \
65} while (0)
66
67#define __MUTEX_INITIALIZER(lockname) \
68 { .owner = ATOMIC_LONG_INIT(0) \
69 , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
70 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
71 __DEBUG_MUTEX_INITIALIZER(lockname) \
72 __DEP_MAP_MUTEX_INITIALIZER(lockname) }
73
74#define DEFINE_MUTEX(mutexname) \
75 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
76
77extern void __mutex_init(struct mutex *lock, const char *name,
78 struct lock_class_key *key);
79
80/**
81 * mutex_is_locked - is the mutex locked
82 * @lock: the mutex to be queried
83 *
84 * Returns true if the mutex is locked, false if unlocked.
85 */
86extern bool mutex_is_locked(struct mutex *lock);
87
88#else /* !CONFIG_PREEMPT_RT */
89/*
90 * Preempt-RT variant based on rtmutexes.
91 */
92
93#define __MUTEX_INITIALIZER(mutexname) \
94{ \
95 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \
96 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \
97}
98
99#define DEFINE_MUTEX(mutexname) \
100 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
101
102extern void __mutex_rt_init(struct mutex *lock, const char *name,
103 struct lock_class_key *key);
104extern int mutex_trylock(struct mutex *lock);
105
106static inline void mutex_destroy(struct mutex *lock) { }
107
108#define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex)
109
110#define __mutex_init(mutex, name, key) \
111do { \
112 rt_mutex_base_init(&(mutex)->rtmutex); \
113 __mutex_rt_init((mutex), name, key); \
114} while (0)
115
116#define mutex_init(mutex) \
117do { \
118 static struct lock_class_key __key; \
119 \
120 __mutex_init((mutex), #mutex, &__key); \
121} while (0)
122#endif /* CONFIG_PREEMPT_RT */
123
124/*
125 * See kernel/locking/mutex.c for detailed documentation of these APIs.
126 * Also see Documentation/locking/mutex-design.rst.
127 */
128#ifdef CONFIG_DEBUG_LOCK_ALLOC
129extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
130extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
131
132extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
133 unsigned int subclass);
134extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
135 unsigned int subclass);
136extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
137
138#define mutex_lock(lock) mutex_lock_nested(lock, 0)
139#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
140#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
141#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
142
143#define mutex_lock_nest_lock(lock, nest_lock) \
144do { \
145 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
146 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
147} while (0)
148
149#else
150extern void mutex_lock(struct mutex *lock);
151extern int __must_check mutex_lock_interruptible(struct mutex *lock);
152extern int __must_check mutex_lock_killable(struct mutex *lock);
153extern void mutex_lock_io(struct mutex *lock);
154
155# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
156# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
157# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
158# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
159# define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
160#endif
161
162/*
163 * NOTE: mutex_trylock() follows the spin_trylock() convention,
164 * not the down_trylock() convention!
165 *
166 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
167 */
168extern int mutex_trylock(struct mutex *lock);
169extern void mutex_unlock(struct mutex *lock);
170
171extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
172
173DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
174DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
175DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
176
177#endif /* __LINUX_MUTEX_H */