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