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 <[email protected]> 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 struct 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 42 extern void mutex_destroy(struct mutex *lock); 43 44 #else 45 46 # define __DEBUG_MUTEX_INITIALIZER(lockname) 47 48 static inline void mutex_destroy(struct mutex *lock) {} 49 50 #endif 51 52 #ifndef CONFIG_PREEMPT_RT 53 /** 54 * mutex_init - initialize the mutex 55 * @mutex: the mutex to be initialized 56 * 57 * Initialize the mutex to unlocked state. 58 * 59 * It is not allowed to initialize an already locked mutex. 60 */ 61 #define mutex_init(mutex) \ 62 do { \ 63 static struct lock_class_key __key; \ 64 \ 65 __mutex_init((mutex), #mutex, &__key); \ 66 } while (0) 67 68 #define __MUTEX_INITIALIZER(lockname) \ 69 { .owner = ATOMIC_LONG_INIT(0) \ 70 , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ 71 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ 72 __DEBUG_MUTEX_INITIALIZER(lockname) \ 73 __DEP_MAP_MUTEX_INITIALIZER(lockname) } 74 75 #define DEFINE_MUTEX(mutexname) \ 76 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) 77 78 extern void __mutex_init(struct mutex *lock, const char *name, 79 struct lock_class_key *key); 80 81 /** 82 * mutex_is_locked - is the mutex locked 83 * @lock: the mutex to be queried 84 * 85 * Returns true if the mutex is locked, false if unlocked. 86 */ 87 extern bool mutex_is_locked(struct mutex *lock); 88 89 #else /* !CONFIG_PREEMPT_RT */ 90 /* 91 * Preempt-RT variant based on rtmutexes. 92 */ 93 94 #define __MUTEX_INITIALIZER(mutexname) \ 95 { \ 96 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \ 97 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \ 98 } 99 100 #define DEFINE_MUTEX(mutexname) \ 101 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) 102 103 extern void __mutex_rt_init(struct mutex *lock, const char *name, 104 struct lock_class_key *key); 105 106 #define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex) 107 108 #define __mutex_init(mutex, name, key) \ 109 do { \ 110 rt_mutex_base_init(&(mutex)->rtmutex); \ 111 __mutex_rt_init((mutex), name, key); \ 112 } while (0) 113 114 #define mutex_init(mutex) \ 115 do { \ 116 static struct lock_class_key __key; \ 117 \ 118 __mutex_init((mutex), #mutex, &__key); \ 119 } while (0) 120 #endif /* CONFIG_PREEMPT_RT */ 121 122 #ifdef CONFIG_DEBUG_MUTEXES 123 124 int __devm_mutex_init(struct device *dev, struct mutex *lock); 125 126 #else 127 128 static inline int __devm_mutex_init(struct device *dev, struct mutex *lock) 129 { 130 /* 131 * When CONFIG_DEBUG_MUTEXES is off mutex_destroy() is just a nop so 132 * no really need to register it in the devm subsystem. 133 */ 134 return 0; 135 } 136 137 #endif 138 139 #define devm_mutex_init(dev, mutex) \ 140 ({ \ 141 typeof(mutex) mutex_ = (mutex); \ 142 \ 143 mutex_init(mutex_); \ 144 __devm_mutex_init(dev, mutex_); \ 145 }) 146 147 /* 148 * See kernel/locking/mutex.c for detailed documentation of these APIs. 149 * Also see Documentation/locking/mutex-design.rst. 150 */ 151 #ifdef CONFIG_DEBUG_LOCK_ALLOC 152 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); 153 extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); 154 155 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, 156 unsigned int subclass); 157 extern int __must_check mutex_lock_killable_nested(struct mutex *lock, 158 unsigned int subclass); 159 extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass); 160 161 #define mutex_lock(lock) mutex_lock_nested(lock, 0) 162 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) 163 #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) 164 #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0) 165 166 #define mutex_lock_nest_lock(lock, nest_lock) \ 167 do { \ 168 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ 169 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ 170 } while (0) 171 172 #else 173 extern void mutex_lock(struct mutex *lock); 174 extern int __must_check mutex_lock_interruptible(struct mutex *lock); 175 extern int __must_check mutex_lock_killable(struct mutex *lock); 176 extern void mutex_lock_io(struct mutex *lock); 177 178 # define mutex_lock_nested(lock, subclass) mutex_lock(lock) 179 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) 180 # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) 181 # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) 182 # define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock) 183 #endif 184 185 /* 186 * NOTE: mutex_trylock() follows the spin_trylock() convention, 187 * not the down_trylock() convention! 188 * 189 * Returns 1 if the mutex has been acquired successfully, and 0 on contention. 190 */ 191 extern int mutex_trylock(struct mutex *lock); 192 extern void mutex_unlock(struct mutex *lock); 193 194 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); 195 196 DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T)) 197 DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T)) 198 DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0) 199 200 #endif /* __LINUX_MUTEX_H */ 201