mutex.h

  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
 89#ifdef CONFIG_DEBUG_LOCK_ALLOC
 90void mutex_init_lockep(struct mutex *lock, const char *name, struct lock_class_key *key);
 91
 92static inline void __mutex_init(struct mutex *lock, const char *name,
 93				struct lock_class_key *key)
 94{
 95	mutex_init_lockep(lock, name, key);
 96}
 97#else
 98extern void mutex_init_generic(struct mutex *lock);
 99
100static inline void __mutex_init(struct mutex *lock, const char *name,
101				struct lock_class_key *key)
102{
103	mutex_init_generic(lock);
104}
105#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
106
107/**
108 * mutex_is_locked - is the mutex locked
109 * @lock: the mutex to be queried
110 *
111 * Returns true if the mutex is locked, false if unlocked.
112 */
113extern bool mutex_is_locked(struct mutex *lock);
114
115#else /* !CONFIG_PREEMPT_RT */
116/*
117 * Preempt-RT variant based on rtmutexes.
118 */
119
120#define __MUTEX_INITIALIZER(mutexname)					\
121{									\
122	.rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex)	\
123	__DEP_MAP_MUTEX_INITIALIZER(mutexname)				\
124}
125
126#define DEFINE_MUTEX(mutexname)						\
127	struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
128
129#define mutex_is_locked(l)	rt_mutex_base_is_locked(&(l)->rtmutex)
130
131#ifdef CONFIG_DEBUG_LOCK_ALLOC
132extern void mutex_rt_init_lockdep(struct mutex *mutex, const char *name,
133			     struct lock_class_key *key);
134
135static inline void __mutex_init(struct mutex *lock, const char *name,
136				struct lock_class_key *key)
137{
138	mutex_rt_init_lockdep(lock, name, key);
139}
140
141#else
142extern void mutex_rt_init_generic(struct mutex *mutex);
143
144static inline void __mutex_init(struct mutex *lock, const char *name,
145				struct lock_class_key *key)
146{
147	mutex_rt_init_generic(lock);
148}
149#endif /* !CONFIG_LOCKDEP */
150#endif /* CONFIG_PREEMPT_RT */
151
152#ifdef CONFIG_DEBUG_MUTEXES
153
154int __must_check __devm_mutex_init(struct device *dev, struct mutex *lock);
155
156#else
157
158static inline int __must_check __devm_mutex_init(struct device *dev, struct mutex *lock)
159{
160	/*
161	 * When CONFIG_DEBUG_MUTEXES is off mutex_destroy() is just a nop so
162	 * no really need to register it in the devm subsystem.
163	 */
164	return 0;
165}
166
167#endif
168
169#define __mutex_init_ret(mutex)				\
170({							\
171	typeof(mutex) mutex_ = (mutex);			\
172							\
173	mutex_init(mutex_);				\
174	mutex_;						\
175})
176
177#define devm_mutex_init(dev, mutex) \
178	__devm_mutex_init(dev, __mutex_init_ret(mutex))
179
180/*
181 * See kernel/locking/mutex.c for detailed documentation of these APIs.
182 * Also see Documentation/locking/mutex-design.rst.
183 */
184#ifdef CONFIG_DEBUG_LOCK_ALLOC
185extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
186extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
187extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
188					unsigned int subclass);
189extern int __must_check _mutex_lock_killable(struct mutex *lock,
190		unsigned int subclass, struct lockdep_map *nest_lock);
191extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
192
193#define mutex_lock(lock) mutex_lock_nested(lock, 0)
194#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
195#define mutex_lock_killable(lock) _mutex_lock_killable(lock, 0, NULL)
196#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
197
198#define mutex_lock_nest_lock(lock, nest_lock)				\
199do {									\
200	typecheck(struct lockdep_map *, &(nest_lock)->dep_map);	\
201	_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map);		\
202} while (0)
203
204#define mutex_lock_killable_nest_lock(lock, nest_lock)			\
205(									\
206	typecheck(struct lockdep_map *, &(nest_lock)->dep_map),		\
207	_mutex_lock_killable(lock, 0, &(nest_lock)->dep_map)		\
208)
209
210#define mutex_lock_killable_nested(lock, subclass) \
211	_mutex_lock_killable(lock, subclass, NULL)
212
213#else
214extern void mutex_lock(struct mutex *lock);
215extern int __must_check mutex_lock_interruptible(struct mutex *lock);
216extern int __must_check mutex_lock_killable(struct mutex *lock);
217extern void mutex_lock_io(struct mutex *lock);
218
219# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
220# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
221# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
222# define mutex_lock_killable_nest_lock(lock, nest_lock) mutex_lock_killable(lock)
223# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
224# define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
225#endif
226
227/*
228 * NOTE: mutex_trylock() follows the spin_trylock() convention,
229 *       not the down_trylock() convention!
230 *
231 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
232 */
233
234#ifdef CONFIG_DEBUG_LOCK_ALLOC
235extern int _mutex_trylock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
236
237#define mutex_trylock_nest_lock(lock, nest_lock)		\
238(								\
239	typecheck(struct lockdep_map *, &(nest_lock)->dep_map),	\
240	_mutex_trylock_nest_lock(lock, &(nest_lock)->dep_map)	\
241)
242
243#define mutex_trylock(lock) _mutex_trylock_nest_lock(lock, NULL)
244#else
245extern int mutex_trylock(struct mutex *lock);
246#define mutex_trylock_nest_lock(lock, nest_lock) mutex_trylock(lock)
247#endif
248
249extern void mutex_unlock(struct mutex *lock);
250
251extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
252
253DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
254DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
255DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T), _RET == 0)
256
257extern unsigned long mutex_get_owner(struct mutex *lock);
258
259#endif /* __LINUX_MUTEX_H */