mutex.h (6808B)
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 23#ifdef CONFIG_DEBUG_LOCK_ALLOC 24# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ 25 , .dep_map = { \ 26 .name = #lockname, \ 27 .wait_type_inner = LD_WAIT_SLEEP, \ 28 } 29#else 30# define __DEP_MAP_MUTEX_INITIALIZER(lockname) 31#endif 32 33#ifndef CONFIG_PREEMPT_RT 34 35/* 36 * Simple, straightforward mutexes with strict semantics: 37 * 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 48 * contexts such as tasklets and timers 49 * 50 * These semantics are fully enforced when DEBUG_MUTEXES is 51 * enabled. Furthermore, besides enforcing the above rules, the mutex 52 * debugging code also implements a number of additional features 53 * that make lock debugging easier and faster: 54 * 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 61 * locks and tasks (and only those tasks) 62 */ 63struct mutex { 64 atomic_long_t owner; 65 raw_spinlock_t wait_lock; 66#ifdef CONFIG_MUTEX_SPIN_ON_OWNER 67 struct optimistic_spin_queue osq; /* Spinner MCS lock */ 68#endif 69 struct list_head wait_list; 70#ifdef CONFIG_DEBUG_MUTEXES 71 void *magic; 72#endif 73#ifdef CONFIG_DEBUG_LOCK_ALLOC 74 struct lockdep_map dep_map; 75#endif 76}; 77 78#ifdef CONFIG_DEBUG_MUTEXES 79 80#define __DEBUG_MUTEX_INITIALIZER(lockname) \ 81 , .magic = &lockname 82 83extern void mutex_destroy(struct mutex *lock); 84 85#else 86 87# define __DEBUG_MUTEX_INITIALIZER(lockname) 88 89static inline void mutex_destroy(struct mutex *lock) {} 90 91#endif 92 93/** 94 * mutex_init - initialize the mutex 95 * @mutex: the mutex to be initialized 96 * 97 * Initialize the mutex to unlocked state. 98 * 99 * It is not allowed to initialize an already locked mutex. 100 */ 101#define mutex_init(mutex) \ 102do { \ 103 static struct lock_class_key __key; \ 104 \ 105 __mutex_init((mutex), #mutex, &__key); \ 106} while (0) 107 108#define __MUTEX_INITIALIZER(lockname) \ 109 { .owner = ATOMIC_LONG_INIT(0) \ 110 , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ 111 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ 112 __DEBUG_MUTEX_INITIALIZER(lockname) \ 113 __DEP_MAP_MUTEX_INITIALIZER(lockname) } 114 115#define DEFINE_MUTEX(mutexname) \ 116 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) 117 118extern void __mutex_init(struct mutex *lock, const char *name, 119 struct lock_class_key *key); 120 121/** 122 * mutex_is_locked - is the mutex locked 123 * @lock: the mutex to be queried 124 * 125 * Returns true if the mutex is locked, false if unlocked. 126 */ 127extern bool mutex_is_locked(struct mutex *lock); 128 129#else /* !CONFIG_PREEMPT_RT */ 130/* 131 * Preempt-RT variant based on rtmutexes. 132 */ 133#include <linux/rtmutex.h> 134 135struct mutex { 136 struct rt_mutex_base rtmutex; 137#ifdef CONFIG_DEBUG_LOCK_ALLOC 138 struct lockdep_map dep_map; 139#endif 140}; 141 142#define __MUTEX_INITIALIZER(mutexname) \ 143{ \ 144 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \ 145 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \ 146} 147 148#define DEFINE_MUTEX(mutexname) \ 149 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) 150 151extern void __mutex_rt_init(struct mutex *lock, const char *name, 152 struct lock_class_key *key); 153extern int mutex_trylock(struct mutex *lock); 154 155static inline void mutex_destroy(struct mutex *lock) { } 156 157#define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex) 158 159#define __mutex_init(mutex, name, key) \ 160do { \ 161 rt_mutex_base_init(&(mutex)->rtmutex); \ 162 __mutex_rt_init((mutex), name, key); \ 163} while (0) 164 165#define mutex_init(mutex) \ 166do { \ 167 static struct lock_class_key __key; \ 168 \ 169 __mutex_init((mutex), #mutex, &__key); \ 170} while (0) 171#endif /* CONFIG_PREEMPT_RT */ 172 173/* 174 * See kernel/locking/mutex.c for detailed documentation of these APIs. 175 * Also see Documentation/locking/mutex-design.rst. 176 */ 177#ifdef CONFIG_DEBUG_LOCK_ALLOC 178extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); 179extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); 180 181extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, 182 unsigned int subclass); 183extern int __must_check mutex_lock_killable_nested(struct mutex *lock, 184 unsigned int subclass); 185extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass); 186 187#define mutex_lock(lock) mutex_lock_nested(lock, 0) 188#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) 189#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) 190#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0) 191 192#define mutex_lock_nest_lock(lock, nest_lock) \ 193do { \ 194 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ 195 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ 196} while (0) 197 198#else 199extern void mutex_lock(struct mutex *lock); 200extern int __must_check mutex_lock_interruptible(struct mutex *lock); 201extern int __must_check mutex_lock_killable(struct mutex *lock); 202extern void mutex_lock_io(struct mutex *lock); 203 204# define mutex_lock_nested(lock, subclass) mutex_lock(lock) 205# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) 206# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) 207# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) 208# define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock) 209#endif 210 211/* 212 * NOTE: mutex_trylock() follows the spin_trylock() convention, 213 * not the down_trylock() convention! 214 * 215 * Returns 1 if the mutex has been acquired successfully, and 0 on contention. 216 */ 217extern int mutex_trylock(struct mutex *lock); 218extern void mutex_unlock(struct mutex *lock); 219 220extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); 221 222#endif /* __LINUX_MUTEX_H */