1 /* SPDX-License-Identifier: GPL-2.0 */
38  * - only one task can hold the mutex at a time
39  * - only the owner can unlock the mutex
40  * - multiple unlocks are not permitted
41  * - recursive locking is not permitted
42  * - a mutex object must be initialized via the API
43  * - a mutex object must not be initialized via memset or copying
44  * - task may not exit with mutex held
45  * - memory areas where held locks reside must not be freed
46  * - held mutexes must not be reinitialized
47  * - mutexes may not be used in hardware or software interrupt
53  * that make lock debugging easier and faster:
55  * - uses symbolic names of mutexes, whenever they are printed in debug output
56  * - point-of-acquire tracking, symbolic lookup of function names
57  * - list of all locks held in the system, printout of them
58  * - owner tracking
59  * - detects self-recursing locks and prints out all relevant info
60  * - detects multi-task circular deadlocks and prints out all affected
67 	struct optimistic_spin_queue osq; /* Spinner MCS lock */
83 extern void mutex_destroy(struct mutex *lock);
89 static inline void mutex_destroy(struct mutex *lock) {}  in mutex_destroy()  argument
94  * mutex_init - initialize the mutex
118 extern void __mutex_init(struct mutex *lock, const char *name,
122  * mutex_is_locked - is the mutex locked
123  * @lock: the mutex to be queried
127 extern bool mutex_is_locked(struct mutex *lock);
131  * Preempt-RT variant based on rtmutexes.
151 extern void __mutex_rt_init(struct mutex *lock, const char *name,
153 extern int mutex_trylock(struct mutex *lock);
155 static inline void mutex_destroy(struct mutex *lock) { }  in mutex_destroy()  argument
157 #define mutex_is_locked(l)	rt_mutex_base_is_locked(&(l)->rtmutex)
161 	rt_mutex_base_init(&(mutex)->rtmutex);		\
175  * Also see Documentation/locking/mutex-design.rst.
178 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
179 extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
181 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
183 extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
185 extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
187 #define mutex_lock(lock) mutex_lock_nested(lock, 0)  argument
188 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)  argument
189 #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)  argument
190 #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)  argument
192 #define mutex_lock_nest_lock(lock, nest_lock)				\  argument
194 	typecheck(struct lockdep_map *, &(nest_lock)->dep_map);	\
195 	_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map);		\
199 extern void mutex_lock(struct mutex *lock);
200 extern int __must_check mutex_lock_interruptible(struct mutex *lock);
201 extern int __must_check mutex_lock_killable(struct mutex *lock);
202 extern void mutex_lock_io(struct mutex *lock);
204 # define mutex_lock_nested(lock, subclass) mutex_lock(lock)  argument
205 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)  argument
206 # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)  argument
207 # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)  argument
208 # define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)  argument
217 extern int mutex_trylock(struct mutex *lock);
218 extern void mutex_unlock(struct mutex *lock);
220 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);