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
20 extern 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 */
30 struct rt_mutex {
31 raw_spinlock_t wait_lock;
32 struct rb_root_cached waiters;
33 struct task_struct *owner;
34 #ifdef CONFIG_DEBUG_RT_MUTEXES
35 int save_state;
36 const char *name, *file;
37 int line;
38 void *magic;
39 #endif
40 #ifdef CONFIG_DEBUG_LOCK_ALLOC
41 struct lockdep_map dep_map;
42 #endif
43 };
44
45 struct rt_mutex_waiter;
46 struct hrtimer_sleeper;
47
48 #ifdef CONFIG_DEBUG_RT_MUTEXES
49 extern int rt_mutex_debug_check_no_locks_freed(const void *from,
50 unsigned long len);
51 extern void rt_mutex_debug_check_no_locks_held(struct task_struct *task);
52 #else
rt_mutex_debug_check_no_locks_freed(const void * from,unsigned long len)53 static inline int rt_mutex_debug_check_no_locks_freed(const void *from,
54 unsigned long len)
55 {
56 return 0;
57 }
58 # define rt_mutex_debug_check_no_locks_held(task) do { } while (0)
59 #endif
60
61 #ifdef CONFIG_DEBUG_RT_MUTEXES
62 # define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
63 , .name = #mutexname, .file = __FILE__, .line = __LINE__
64
65 # define rt_mutex_init(mutex) \
66 do { \
67 static struct lock_class_key __key; \
68 __rt_mutex_init(mutex, __func__, &__key); \
69 } while (0)
70
71 extern void rt_mutex_debug_task_free(struct task_struct *tsk);
72 #else
73 # define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
74 # define rt_mutex_init(mutex) __rt_mutex_init(mutex, NULL, NULL)
75 # define rt_mutex_debug_task_free(t) do { } while (0)
76 #endif
77
78 #ifdef CONFIG_DEBUG_LOCK_ALLOC
79 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname) \
80 , .dep_map = { .name = #mutexname }
81 #else
82 #define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)
83 #endif
84
85 #define __RT_MUTEX_INITIALIZER(mutexname) \
86 { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
87 , .waiters = RB_ROOT_CACHED \
88 , .owner = NULL \
89 __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
90 __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)}
91
92 #define DEFINE_RT_MUTEX(mutexname) \
93 struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
94
95 /**
96 * rt_mutex_is_locked - is the mutex locked
97 * @lock: the mutex to be queried
98 *
99 * Returns 1 if the mutex is locked, 0 if unlocked.
100 */
rt_mutex_is_locked(struct rt_mutex * lock)101 static inline int rt_mutex_is_locked(struct rt_mutex *lock)
102 {
103 return lock->owner != NULL;
104 }
105
106 extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
107 extern void rt_mutex_destroy(struct rt_mutex *lock);
108
109 #ifdef CONFIG_DEBUG_LOCK_ALLOC
110 extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
111 #define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
112 #else
113 extern void rt_mutex_lock(struct rt_mutex *lock);
114 #define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
115 #endif
116
117 extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
118 extern int rt_mutex_timed_lock(struct rt_mutex *lock,
119 struct hrtimer_sleeper *timeout);
120
121 extern int rt_mutex_trylock(struct rt_mutex *lock);
122
123 extern void rt_mutex_unlock(struct rt_mutex *lock);
124
125 #endif
126