include/linux/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
  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 /**
  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)                                               \
  61 do {                                                                    \
  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 extern void __mutex_init(struct mutex *lock, const char *name,
  90                          struct lock_class_key *key);
  91
  92 /**
  93  * mutex_is_locked - is the mutex locked
  94  * @lock: the mutex to be queried
  95  *
  96  * Returns true if the mutex is locked, false if unlocked.
  97  */
  98 extern bool mutex_is_locked(struct mutex *lock);
  99
 100 #else /* !CONFIG_PREEMPT_RT */
 101 /*
 102  * Preempt-RT variant based on rtmutexes.
 103  */
 104
 105 #define __MUTEX_INITIALIZER(mutexname)                                  \
 106 {                                                                       \
 107         .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex)       \
 108         __DEP_MAP_MUTEX_INITIALIZER(mutexname)                          \
 109 }
 110
 111 #define DEFINE_MUTEX(mutexname)                                         \
 112         struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
 113
 114 extern void __mutex_rt_init(struct mutex *lock, const char *name,
 115                             struct lock_class_key *key);
 116
 117 #define mutex_is_locked(l)      rt_mutex_base_is_locked(&(l)->rtmutex)
 118
 119 #define __mutex_init(mutex, name, key)                  \
 120 do {                                                    \
 121         rt_mutex_base_init(&(mutex)->rtmutex);          \
 122         __mutex_rt_init((mutex), name, key);            \
 123 } while (0)
 124
 125 #endif /* CONFIG_PREEMPT_RT */
 126
 127 #ifdef CONFIG_DEBUG_MUTEXES
 128
 129 int __devm_mutex_init(struct device *dev, struct mutex *lock);
 130
 131 #else
 132
 133 static inline int __devm_mutex_init(struct device *dev, struct mutex *lock)
 134 {
 135         /*
 136          * When CONFIG_DEBUG_MUTEXES is off mutex_destroy() is just a nop so
 137          * no really need to register it in the devm subsystem.
 138          */
 139         return 0;
 140 }
 141
 142 #endif
 143
 144 #define devm_mutex_init(dev, mutex)                     \
 145 ({                                                      \
 146         typeof(mutex) mutex_ = (mutex);                 \
 147                                                         \
 148         mutex_init(mutex_);                             \
 149         __devm_mutex_init(dev, mutex_);                 \
 150 })
 151
 152 /*
 153  * See kernel/locking/mutex.c for detailed documentation of these APIs.
 154  * Also see Documentation/locking/mutex-design.rst.
 155  */
 156 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 157 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
 158 extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
 159
 160 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
 161                                         unsigned int subclass);
 162 extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
 163                                         unsigned int subclass);
 164 extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
 165
 166 #define mutex_lock(lock) mutex_lock_nested(lock, 0)
 167 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
 168 #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
 169 #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
 170
 171 #define mutex_lock_nest_lock(lock, nest_lock)                           \
 172 do {                                                                    \
 173         typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
 174         _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map);             \
 175 } while (0)
 176
 177 #else
 178 extern void mutex_lock(struct mutex *lock);
 179 extern int __must_check mutex_lock_interruptible(struct mutex *lock);
 180 extern int __must_check mutex_lock_killable(struct mutex *lock);
 181 extern void mutex_lock_io(struct mutex *lock);
 182
 183 # define mutex_lock_nested(lock, subclass) mutex_lock(lock)
 184 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
 185 # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
 186 # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
 187 # define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
 188 #endif
 189
 190 /*
 191  * NOTE: mutex_trylock() follows the spin_trylock() convention,
 192  *       not the down_trylock() convention!
 193  *
 194  * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
 195  */
 196 extern int mutex_trylock(struct mutex *lock);
 197 extern void mutex_unlock(struct mutex *lock);
 198
 199 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
 200
 201 DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
 202 DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
 203 DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
 204
 205 #endif /* __LINUX_MUTEX_H */