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
168
169
170
171
172
|
#ifndef _LINUX_SWAIT_H
#define _LINUX_SWAIT_H
#include <linux/list.h>
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <asm/current.h>
/*
* Simple wait queues
*
* While these are very similar to the other/complex wait queues (wait.h) the
* most important difference is that the simple waitqueue allows for
* deterministic behaviour -- IOW it has strictly bounded IRQ and lock hold
* times.
*
* In order to make this so, we had to drop a fair number of features of the
* other waitqueue code; notably:
*
* - mixing INTERRUPTIBLE and UNINTERRUPTIBLE sleeps on the same waitqueue;
* all wakeups are TASK_NORMAL in order to avoid O(n) lookups for the right
* sleeper state.
*
* - the exclusive mode; because this requires preserving the list order
* and this is hard.
*
* - custom wake functions; because you cannot give any guarantees about
* random code.
*
* As a side effect of this; the data structures are slimmer.
*
* One would recommend using this wait queue where possible.
*/
struct task_struct;
struct swait_queue_head {
raw_spinlock_t lock;
struct list_head task_list;
};
struct swait_queue {
struct task_struct *task;
struct list_head task_list;
};
#define __SWAITQUEUE_INITIALIZER(name) { \
.task = current, \
.task_list = LIST_HEAD_INIT((name).task_list), \
}
#define DECLARE_SWAITQUEUE(name) \
struct swait_queue name = __SWAITQUEUE_INITIALIZER(name)
#define __SWAIT_QUEUE_HEAD_INITIALIZER(name) { \
.lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock), \
.task_list = LIST_HEAD_INIT((name).task_list), \
}
#define DECLARE_SWAIT_QUEUE_HEAD(name) \
struct swait_queue_head name = __SWAIT_QUEUE_HEAD_INITIALIZER(name)
extern void __init_swait_queue_head(struct swait_queue_head *q, const char *name,
struct lock_class_key *key);
#define init_swait_queue_head(q) \
do { \
static struct lock_class_key __key; \
__init_swait_queue_head((q), #q, &__key); \
} while (0)
#ifdef CONFIG_LOCKDEP
# define __SWAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
({ init_swait_queue_head(&name); name; })
# define DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(name) \
struct swait_queue_head name = __SWAIT_QUEUE_HEAD_INIT_ONSTACK(name)
#else
# define DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(name) \
DECLARE_SWAIT_QUEUE_HEAD(name)
#endif
static inline int swait_active(struct swait_queue_head *q)
{
return !list_empty(&q->task_list);
}
extern void swake_up(struct swait_queue_head *q);
extern void swake_up_all(struct swait_queue_head *q);
extern void swake_up_locked(struct swait_queue_head *q);
extern void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait);
extern void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state);
extern long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state);
extern void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait);
extern void finish_swait(struct swait_queue_head *q, struct swait_queue *wait);
/* as per ___wait_event() but for swait, therefore "exclusive == 0" */
#define ___swait_event(wq, condition, state, ret, cmd) \
({ \
struct swait_queue __wait; \
long __ret = ret; \
\
INIT_LIST_HEAD(&__wait.task_list); \
for (;;) { \
long __int = prepare_to_swait_event(&wq, &__wait, state);\
\
if (condition) \
break; \
\
if (___wait_is_interruptible(state) && __int) { \
__ret = __int; \
break; \
} \
\
cmd; \
} \
finish_swait(&wq, &__wait); \
__ret; \
})
#define __swait_event(wq, condition) \
(void)___swait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, \
schedule())
#define swait_event(wq, condition) \
do { \
if (condition) \
break; \
__swait_event(wq, condition); \
} while (0)
#define __swait_event_timeout(wq, condition, timeout) \
___swait_event(wq, ___wait_cond_timeout(condition), \
TASK_UNINTERRUPTIBLE, timeout, \
__ret = schedule_timeout(__ret))
#define swait_event_timeout(wq, condition, timeout) \
({ \
long __ret = timeout; \
if (!___wait_cond_timeout(condition)) \
__ret = __swait_event_timeout(wq, condition, timeout); \
__ret; \
})
#define __swait_event_interruptible(wq, condition) \
___swait_event(wq, condition, TASK_INTERRUPTIBLE, 0, \
schedule())
#define swait_event_interruptible(wq, condition) \
({ \
int __ret = 0; \
if (!(condition)) \
__ret = __swait_event_interruptible(wq, condition); \
__ret; \
})
#define __swait_event_interruptible_timeout(wq, condition, timeout) \
___swait_event(wq, ___wait_cond_timeout(condition), \
TASK_INTERRUPTIBLE, timeout, \
__ret = schedule_timeout(__ret))
#define swait_event_interruptible_timeout(wq, condition, timeout) \
({ \
long __ret = timeout; \
if (!___wait_cond_timeout(condition)) \
__ret = __swait_event_interruptible_timeout(wq, \
condition, timeout); \
__ret; \
})
#endif /* _LINUX_SWAIT_H */
|
