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
21extern int max_lock_depth; /* for sysctl */
22
23struct 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 */
42static inline bool rt_mutex_base_is_locked(struct rt_mutex_base *lock)
43{
44 return READ_ONCE(lock->owner) != NULL;
45}
46
47extern 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 */
57struct rt_mutex {
58 struct rt_mutex_base rtmutex;
59#ifdef CONFIG_DEBUG_LOCK_ALLOC
60 struct lockdep_map dep_map;
61#endif
62};
63
64struct rt_mutex_waiter;
65struct hrtimer_sleeper;
66
67#ifdef CONFIG_DEBUG_RT_MUTEXES
68extern void rt_mutex_debug_task_free(struct task_struct *tsk);
69#else
70static inline void rt_mutex_debug_task_free(struct task_struct *tsk) { }
71#endif
72
73#define rt_mutex_init(mutex) \
74do { \
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
98extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
99
100#ifdef CONFIG_DEBUG_LOCK_ALLOC
101extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
102extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock);
103#define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
104#define rt_mutex_lock_nest_lock(lock, nest_lock) \
105 do { \
106 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
107 _rt_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
108 } while (0)
109
110#else
111extern void rt_mutex_lock(struct rt_mutex *lock);
112#define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
113#define rt_mutex_lock_nest_lock(lock, nest_lock) rt_mutex_lock(lock)
114#endif
115
116extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
117extern int rt_mutex_lock_killable(struct rt_mutex *lock);
118extern int rt_mutex_trylock(struct rt_mutex *lock);
119
120extern void rt_mutex_unlock(struct rt_mutex *lock);
121
122#endif
123

source code of linux/include/linux/rtmutex.h