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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
25struct 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
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/**
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
89extern 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 */
98extern 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
114extern 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) \
120do { \
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
129int __devm_mutex_init(struct device *dev, struct mutex *lock);
130
131#else
132
133static inline int __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 devm_mutex_init(dev, mutex) \
145({ \
146 typeof(mutex) mutex_ = (mutex); \
147 \
148 mutex_init(mutex_); \
149 __devm_mutex_init(dev, mutex_); \
150})
151
152/*
153 * See kernel/locking/mutex.c for detailed documentation of these APIs.
154 * Also see Documentation/locking/mutex-design.rst.
155 */
156#ifdef CONFIG_DEBUG_LOCK_ALLOC
157extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
158extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
159
160extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
161 unsigned int subclass);
162extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
163 unsigned int subclass);
164extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
165
166#define mutex_lock(lock) mutex_lock_nested(lock, 0)
167#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
168#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
169#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
170
171#define mutex_lock_nest_lock(lock, nest_lock) \
172do { \
173 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
174 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
175} while (0)
176
177#else
178extern void mutex_lock(struct mutex *lock);
179extern int __must_check mutex_lock_interruptible(struct mutex *lock);
180extern int __must_check mutex_lock_killable(struct mutex *lock);
181extern void mutex_lock_io(struct mutex *lock);
182
183# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
184# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
185# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
186# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
187# define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
188#endif
189
190/*
191 * NOTE: mutex_trylock() follows the spin_trylock() convention,
192 * not the down_trylock() convention!
193 *
194 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
195 */
196extern int mutex_trylock(struct mutex *lock);
197extern void mutex_unlock(struct mutex *lock);
198
199extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
200
201DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
202DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
203DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
204
205#endif /* __LINUX_MUTEX_H */