include/linux/rtmutex.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * RT Mutexes: blocking mutual exclusion locks with PI support
   4  *
   5  * started by Ingo Molnar and Thomas Gleixner:
   6  *
   7  *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   8  *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
   9  *
  10  * This file contains the public data structure and API definitions.
  11  */
  12
  13 #ifndef __LINUX_RT_MUTEX_H
  14 #define __LINUX_RT_MUTEX_H
  15
  16 #include <linux/compiler.h>
  17 #include <linux/linkage.h>
  18 #include <linux/rbtree_types.h>
  19 #include <linux/spinlock_types_raw.h>
  20
  21 extern int max_lock_depth; /* for sysctl */
  22
  23 struct rt_mutex_base {
  24         raw_spinlock_t          wait_lock;
  25         struct rb_root_cached   waiters;
  26         struct task_struct      *owner;
  27 };
  28
  29 #define __RT_MUTEX_BASE_INITIALIZER(rtbasename)                         \
  30 {                                                                       \
  31         .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(rtbasename.wait_lock),    \
  32         .waiters = RB_ROOT_CACHED,                                      \
  33         .owner = NULL                                                   \
  34 }
  35
  36 /**
  37  * rt_mutex_base_is_locked - is the rtmutex locked
  38  * @lock: the mutex to be queried
  39  *
  40  * Returns true if the mutex is locked, false if unlocked.
  41  */
  42 static inline bool rt_mutex_base_is_locked(struct rt_mutex_base *lock)
  43 {
  44         return READ_ONCE(lock->owner) != NULL;
  45 }
  46
  47 extern void rt_mutex_base_init(struct rt_mutex_base *rtb);
  48
  49 /**
  50  * The rt_mutex structure
  51  *
  52  * @wait_lock:  spinlock to protect the structure
  53  * @waiters:    rbtree root to enqueue waiters in priority order;
  54  *              caches top-waiter (leftmost node).
  55  * @owner:      the mutex owner
  56  */
  57 struct rt_mutex {
  58         struct rt_mutex_base    rtmutex;
  59 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  60         struct lockdep_map      dep_map;
  61 #endif
  62 };
  63
  64 struct rt_mutex_waiter;
  65 struct hrtimer_sleeper;
  66
  67 #ifdef CONFIG_DEBUG_RT_MUTEXES
  68 extern void rt_mutex_debug_task_free(struct task_struct *tsk);
  69 #else
  70 static inline void rt_mutex_debug_task_free(struct task_struct *tsk) { }
  71 #endif
  72
  73 #define rt_mutex_init(mutex) \
  74 do { \
  75         static struct lock_class_key __key; \
  76         __rt_mutex_init(mutex, __func__, &__key); \
  77 } while (0)
  78
  79 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  80 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)       \
  81         .dep_map = {                                    \
  82                 .name = #mutexname,                     \
  83                 .wait_type_inner = LD_WAIT_SLEEP,       \
  84         }
  85 #else
  86 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)
  87 #endif
  88
  89 #define __RT_MUTEX_INITIALIZER(mutexname)                               \
  90 {                                                                       \
  91         .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex),      \
  92         __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)                       \
  93 }
  94
  95 #define DEFINE_RT_MUTEX(mutexname) \
  96         struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
  97
  98 extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
  99
 100 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 101 extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
 102 #define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
 103 #else
 104 extern void rt_mutex_lock(struct rt_mutex *lock);
 105 #define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
 106 #endif
 107
 108 extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
 109 extern int rt_mutex_trylock(struct rt_mutex *lock);
 110
 111 extern void rt_mutex_unlock(struct rt_mutex *lock);
 112
 113 #endif