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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;
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
47#ifdef CONFIG_RT_MUTEXES
48#define RT_MUTEX_HAS_WAITERS 1UL
49
50static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock)
51{
52 unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
53
54 return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
55}
56#endif
57extern void rt_mutex_base_init(struct rt_mutex_base *rtb);
58
59/**
60 * The rt_mutex structure
61 *
62 * @wait_lock: spinlock to protect the structure
63 * @waiters: rbtree root to enqueue waiters in priority order;
64 * caches top-waiter (leftmost node).
65 * @owner: the mutex owner
66 */
67struct rt_mutex {
68 struct rt_mutex_base rtmutex;
69#ifdef CONFIG_DEBUG_LOCK_ALLOC
70 struct lockdep_map dep_map;
71#endif
72};
73
74struct rt_mutex_waiter;
75struct hrtimer_sleeper;
76
77#ifdef CONFIG_DEBUG_RT_MUTEXES
78extern void rt_mutex_debug_task_free(struct task_struct *tsk);
79#else
80static inline void rt_mutex_debug_task_free(struct task_struct *tsk) { }
81#endif
82
83#define rt_mutex_init(mutex) \
84do { \
85 static struct lock_class_key __key; \
86 __rt_mutex_init(mutex, __func__, &__key); \
87} while (0)
88
89#ifdef CONFIG_DEBUG_LOCK_ALLOC
90#define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname) \
91 .dep_map = { \
92 .name = #mutexname, \
93 .wait_type_inner = LD_WAIT_SLEEP, \
94 }
95#else
96#define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)
97#endif
98
99#define __RT_MUTEX_INITIALIZER(mutexname) \
100{ \
101 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex), \
102 __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname) \
103}
104
105#define DEFINE_RT_MUTEX(mutexname) \
106 struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
107
108extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
109
110#ifdef CONFIG_DEBUG_LOCK_ALLOC
111extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
112extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock);
113#define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
114#define rt_mutex_lock_nest_lock(lock, nest_lock) \
115 do { \
116 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
117 _rt_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
118 } while (0)
119
120#else
121extern void rt_mutex_lock(struct rt_mutex *lock);
122#define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
123#define rt_mutex_lock_nest_lock(lock, nest_lock) rt_mutex_lock(lock)
124#endif
125
126extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
127extern int rt_mutex_lock_killable(struct rt_mutex *lock);
128extern int rt_mutex_trylock(struct rt_mutex *lock);
129
130extern void rt_mutex_unlock(struct rt_mutex *lock);
131
132#endif
133

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