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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/linkage.h>
17#include <linux/rbtree.h>
18#include <linux/spinlock_types.h>
19
20extern 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 */
30struct 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
39struct rt_mutex_waiter;
40struct hrtimer_sleeper;
41
42#ifdef CONFIG_DEBUG_RT_MUTEXES
43extern void rt_mutex_debug_task_free(struct task_struct *tsk);
44#else
45static inline void rt_mutex_debug_task_free(struct task_struct *tsk) { }
46#endif
47
48#define rt_mutex_init(mutex) \
49do { \
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 */
76static inline int rt_mutex_is_locked(struct rt_mutex *lock)
77{
78 return lock->owner != NULL;
79}
80
81extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
82
83#ifdef CONFIG_DEBUG_LOCK_ALLOC
84extern 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
87extern void rt_mutex_lock(struct rt_mutex *lock);
88#define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
89#endif
90
91extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
92extern int rt_mutex_trylock(struct rt_mutex *lock);
93
94extern void rt_mutex_unlock(struct rt_mutex *lock);
95
96#endif