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