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 #define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
103 #else
104 extern void rt_mutex_lock(struct rt_mutex *lock);
105 #define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
106 #endif
107
108 extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
109 extern int rt_mutex_trylock(struct rt_mutex *lock);
110
111 extern void rt_mutex_unlock(struct rt_mutex *lock);
112
113 #endif
114