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/linkage.h>
  17 #include <linux/rbtree.h>
  18 #include <linux/spinlock_types.h>
  19
  20 extern int max_lock_depth; /* for sysctl */
  21
  22 /**
  23  * The rt_mutex structure
  24  *
  25  * @wait_lock:  spinlock to protect the structure
  26  * @waiters:    rbtree root to enqueue waiters in priority order;
  27  *              caches top-waiter (leftmost node).
  28  * @owner:      the mutex owner
  29  */
  30 struct rt_mutex {
  31         raw_spinlock_t          wait_lock;
  32         struct rb_root_cached   waiters;
  33         struct task_struct      *owner;
  34 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  35         struct lockdep_map      dep_map;
  36 #endif
  37 };
  38
  39 struct rt_mutex_waiter;
  40 struct hrtimer_sleeper;
  41
  42 #ifdef CONFIG_DEBUG_RT_MUTEXES
  43 extern void rt_mutex_debug_task_free(struct task_struct *tsk);
  44 #else
  45 static inline void rt_mutex_debug_task_free(struct task_struct *tsk) { }
  46 #endif
  47
  48 #define rt_mutex_init(mutex) \
  49 do { \
  50         static struct lock_class_key __key; \
  51         __rt_mutex_init(mutex, __func__, &__key); \
  52 } while (0)
  53
  54 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  55 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname) \
  56         , .dep_map = { .name = #mutexname }
  57 #else
  58 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)
  59 #endif
  60
  61 #define __RT_MUTEX_INITIALIZER(mutexname) \
  62         { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
  63         , .waiters = RB_ROOT_CACHED \
  64         , .owner = NULL \
  65         __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)}
  66
  67 #define DEFINE_RT_MUTEX(mutexname) \
  68         struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
  69
  70 /**
  71  * rt_mutex_is_locked - is the mutex locked
  72  * @lock: the mutex to be queried
  73  *
  74  * Returns 1 if the mutex is locked, 0 if unlocked.
  75  */
  76 static inline int rt_mutex_is_locked(struct rt_mutex *lock)
  77 {
  78         return lock->owner != NULL;
  79 }
  80
  81 extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
  82
  83 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  84 extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
  85 #define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
  86 #else
  87 extern void rt_mutex_lock(struct rt_mutex *lock);
  88 #define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
  89 #endif
  90
  91 extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
  92 extern int rt_mutex_trylock(struct rt_mutex *lock);
  93
  94 extern void rt_mutex_unlock(struct rt_mutex *lock);
  95
  96 #endif