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 #ifdef CONFIG_DEBUG_MUTEXES 36 37 # define __DEBUG_MUTEX_INITIALIZER(lockname) \ 38 , .magic = &lockname 39 40 extern void mutex_destroy(struct mutex *lock); 41 42 #else 43 44 # define __DEBUG_MUTEX_INITIALIZER(lockname) 45 46 static inline void mutex_destroy(struct mutex *lock) {} 47 48 #endif 49 50 #ifndef CONFIG_PREEMPT_RT 51 /** 52 * mutex_init - initialize the mutex 53 * @mutex: the mutex to be initialized 54 * 55 * Initialize the mutex to unlocked state. 56 * 57 * It is not allowed to initialize an already locked mutex. 58 */ 59 #define mutex_init(mutex) \ 60 do { \ 61 static struct lock_class_key __key; \ 62 \ 63 __mutex_init((mutex), #mutex, &__key); \ 64 } while (0) 65 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) } 72 73 #define DEFINE_MUTEX(mutexname) \ 74 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) 75 76 extern void __mutex_init(struct mutex *lock, const char *name, 77 struct lock_class_key *key); 78 79 /** 80 * mutex_is_locked - is the mutex locked 81 * @lock: the mutex to be queried 82 * 83 * Returns true if the mutex is locked, false if unlocked. 84 */ 85 extern bool mutex_is_locked(struct mutex *lock); 86 87 #else /* !CONFIG_PREEMPT_RT */ 88 /* 89 * Preempt-RT variant based on rtmutexes. 90 */ 91 92 #define __MUTEX_INITIALIZER(mutexname) \ 93 { \ 94 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \ 95 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \ 96 } 97 98 #define DEFINE_MUTEX(mutexname) \ 99 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) 100 101 extern void __mutex_rt_init(struct mutex *lock, const char *name, 102 struct lock_class_key *key); 103 104 #define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex) 105 106 #define __mutex_init(mutex, name, key) \ 107 do { \ 108 rt_mutex_base_init(&(mutex)->rtmutex); \ 109 __mutex_rt_init((mutex), name, key); \ 110 } while (0) 111 112 #define mutex_init(mutex) \ 113 do { \ 114 static struct lock_class_key __key; \ 115 \ 116 __mutex_init((mutex), #mutex, &__key); \ 117 } while (0) 118 #endif /* CONFIG_PREEMPT_RT */ 119 120 /* 121 * See kernel/locking/mutex.c for detailed documentation of these APIs. 122 * Also see Documentation/locking/mutex-design.rst. 123 */ 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); 127 128 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); 133 134 #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) 138 139 #define mutex_lock_nest_lock(lock, nest_lock) \ 140 do { \ 141 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ 142 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ 143 } while (0) 144 145 #else 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); 150 151 # 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) 156 #endif 157 158 /* 159 * NOTE: mutex_trylock() follows the spin_trylock() convention, 160 * not the down_trylock() convention! 161 * 162 * Returns 1 if the mutex has been acquired successfully, and 0 on contention. 163 */ 164 extern int mutex_trylock(struct mutex *lock); 165 extern void mutex_unlock(struct mutex *lock); 166 167 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); 168 169 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) 172 173 #endif /* __LINUX_MUTEX_H */ 174