1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
#ifndef _LINUX_RWSEM_RT_H
#define _LINUX_RWSEM_RT_H
#ifndef _LINUX_RWSEM_H
#error "Include rwsem.h"
#endif
/*
* RW-semaphores are a spinlock plus a reader-depth count.
*
* Note that the semantics are different from the usual
* Linux rw-sems, in PREEMPT_RT mode we do not allow
* multiple readers to hold the lock at once, we only allow
* a read-lock owner to read-lock recursively. This is
* better for latency, makes the implementation inherently
* fair and makes it simpler as well.
*/
#include <linux/rtmutex.h>
struct rw_semaphore {
struct rt_mutex lock;
int read_depth;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
};
#define __RWSEM_INITIALIZER(name) \
{ .lock = __RT_MUTEX_INITIALIZER(name.lock), \
RW_DEP_MAP_INIT(name) }
#define DECLARE_RWSEM(lockname) \
struct rw_semaphore lockname = __RWSEM_INITIALIZER(lockname)
extern void __rt_rwsem_init(struct rw_semaphore *rwsem, const char *name,
struct lock_class_key *key);
#define __rt_init_rwsem(sem, name, key) \
do { \
rt_mutex_init(&(sem)->lock); \
__rt_rwsem_init((sem), (name), (key));\
} while (0)
#define __init_rwsem(sem, name, key) __rt_init_rwsem(sem, name, key)
# define rt_init_rwsem(sem) \
do { \
static struct lock_class_key __key; \
\
__rt_init_rwsem((sem), #sem, &__key); \
} while (0)
extern void rt_down_write(struct rw_semaphore *rwsem);
extern int rt_down_write_killable(struct rw_semaphore *rwsem);
extern void rt_down_read_nested(struct rw_semaphore *rwsem, int subclass);
extern void rt_down_write_nested(struct rw_semaphore *rwsem, int subclass);
extern int rt_down_write_killable_nested(struct rw_semaphore *rwsem,
int subclass);
extern void rt_down_write_nested_lock(struct rw_semaphore *rwsem,
struct lockdep_map *nest);
extern void rt__down_read(struct rw_semaphore *rwsem);
extern void rt_down_read(struct rw_semaphore *rwsem);
extern int rt_down_write_trylock(struct rw_semaphore *rwsem);
extern int rt__down_read_trylock(struct rw_semaphore *rwsem);
extern int rt_down_read_trylock(struct rw_semaphore *rwsem);
extern void __rt_up_read(struct rw_semaphore *rwsem);
extern void rt_up_read(struct rw_semaphore *rwsem);
extern void rt_up_write(struct rw_semaphore *rwsem);
extern void rt_downgrade_write(struct rw_semaphore *rwsem);
#define init_rwsem(sem) rt_init_rwsem(sem)
#define rwsem_is_locked(s) rt_mutex_is_locked(&(s)->lock)
static inline int rwsem_is_contended(struct rw_semaphore *sem)
{
/* rt_mutex_has_waiters() */
return !RB_EMPTY_ROOT(&sem->lock.waiters);
}
static inline void __down_read(struct rw_semaphore *sem)
{
rt__down_read(sem);
}
static inline void down_read(struct rw_semaphore *sem)
{
rt_down_read(sem);
}
static inline int __down_read_trylock(struct rw_semaphore *sem)
{
return rt__down_read_trylock(sem);
}
static inline int down_read_trylock(struct rw_semaphore *sem)
{
return rt_down_read_trylock(sem);
}
static inline void down_write(struct rw_semaphore *sem)
{
rt_down_write(sem);
}
static inline int down_write_killable(struct rw_semaphore *sem)
{
return rt_down_write_killable(sem);
}
static inline int down_write_trylock(struct rw_semaphore *sem)
{
return rt_down_write_trylock(sem);
}
static inline void __up_read(struct rw_semaphore *sem)
{
__rt_up_read(sem);
}
static inline void up_read(struct rw_semaphore *sem)
{
rt_up_read(sem);
}
static inline void up_write(struct rw_semaphore *sem)
{
rt_up_write(sem);
}
static inline void downgrade_write(struct rw_semaphore *sem)
{
rt_downgrade_write(sem);
}
static inline void down_read_nested(struct rw_semaphore *sem, int subclass)
{
return rt_down_read_nested(sem, subclass);
}
static inline void down_write_nested(struct rw_semaphore *sem, int subclass)
{
rt_down_write_nested(sem, subclass);
}
static inline int down_write_killable_nested(struct rw_semaphore *sem,
int subclass)
{
return rt_down_write_killable_nested(sem, subclass);
}
#ifdef CONFIG_DEBUG_LOCK_ALLOC
static inline void down_write_nest_lock(struct rw_semaphore *sem,
struct rw_semaphore *nest_lock)
{
rt_down_write_nested_lock(sem, &nest_lock->dep_map);
}
#else
static inline void down_write_nest_lock(struct rw_semaphore *sem,
struct rw_semaphore *nest_lock)
{
rt_down_write_nested_lock(sem, NULL);
}
#endif
#endif
|
