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_RT_MUTEXES
  35         int                     save_state;
  36         const char              *name, *file;
  37         int                     line;
  38         void                    *magic;
  39 #endif
  40 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  41         struct lockdep_map      dep_map;
  42 #endif
  43 };
  44
  45 struct rt_mutex_waiter;
  46 struct hrtimer_sleeper;
  47
  48 #ifdef CONFIG_DEBUG_RT_MUTEXES
  49  extern int rt_mutex_debug_check_no_locks_freed(const void *from,
  50                                                 unsigned long len);
  51  extern void rt_mutex_debug_check_no_locks_held(struct task_struct *task);
  52 #else
  53  static inline int rt_mutex_debug_check_no_locks_freed(const void *from,
  54                                                        unsigned long len)
  55  {
  56         return 0;
  57  }
  58 # define rt_mutex_debug_check_no_locks_held(task)       do { } while (0)
  59 #endif
  60
  61 #ifdef CONFIG_DEBUG_RT_MUTEXES
  62 # define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
  63         , .name = #mutexname, .file = __FILE__, .line = __LINE__
  64
  65 # define rt_mutex_init(mutex) \
  66 do { \
  67         static struct lock_class_key __key; \
  68         __rt_mutex_init(mutex, __func__, &__key); \
  69 } while (0)
  70
  71  extern void rt_mutex_debug_task_free(struct task_struct *tsk);
  72 #else
  73 # define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
  74 # define rt_mutex_init(mutex)                   __rt_mutex_init(mutex, NULL, NULL)
  75 # define rt_mutex_debug_task_free(t)                    do { } while (0)
  76 #endif
  77
  78 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  79 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname) \
  80         , .dep_map = { .name = #mutexname }
  81 #else
  82 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)
  83 #endif
  84
  85 #define __RT_MUTEX_INITIALIZER(mutexname) \
  86         { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
  87         , .waiters = RB_ROOT_CACHED \
  88         , .owner = NULL \
  89         __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
  90         __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)}
  91
  92 #define DEFINE_RT_MUTEX(mutexname) \
  93         struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
  94
  95 /**
  96  * rt_mutex_is_locked - is the mutex locked
  97  * @lock: the mutex to be queried
  98  *
  99  * Returns 1 if the mutex is locked, 0 if unlocked.
 100  */
 101 static inline int rt_mutex_is_locked(struct rt_mutex *lock)
 102 {
 103         return lock->owner != NULL;
 104 }
 105
 106 extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
 107 extern void rt_mutex_destroy(struct rt_mutex *lock);
 108
 109 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 110 extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
 111 #define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
 112 #else
 113 extern void rt_mutex_lock(struct rt_mutex *lock);
 114 #define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
 115 #endif
 116
 117 extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
 118 extern int rt_mutex_timed_lock(struct rt_mutex *lock,
 119                                struct hrtimer_sleeper *timeout);
 120
 121 extern int rt_mutex_trylock(struct rt_mutex *lock);
 122
 123 extern void rt_mutex_unlock(struct rt_mutex *lock);
 124
 125 #endif