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
|
#include <linux/sched/signal.h>
#include <linux/swait.h>
void __init_swait_queue_head(struct swait_queue_head *q, const char *name,
struct lock_class_key *key)
{
raw_spin_lock_init(&q->lock);
lockdep_set_class_and_name(&q->lock, key, name);
INIT_LIST_HEAD(&q->task_list);
}
EXPORT_SYMBOL(__init_swait_queue_head);
/*
* The thing about the wake_up_state() return value; I think we can ignore it.
*
* If for some reason it would return 0, that means the previously waiting
* task is already running, so it will observe condition true (or has already).
*/
void swake_up_locked(struct swait_queue_head *q)
{
struct swait_queue *curr;
if (list_empty(&q->task_list))
return;
curr = list_first_entry(&q->task_list, typeof(*curr), task_list);
wake_up_process(curr->task);
list_del_init(&curr->task_list);
}
EXPORT_SYMBOL(swake_up_locked);
void swake_up(struct swait_queue_head *q)
{
unsigned long flags;
raw_spin_lock_irqsave(&q->lock, flags);
swake_up_locked(q);
raw_spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(swake_up);
/*
* Does not allow usage from IRQ disabled, since we must be able to
* release IRQs to guarantee bounded hold time.
*/
void swake_up_all(struct swait_queue_head *q)
{
struct swait_queue *curr;
LIST_HEAD(tmp);
raw_spin_lock_irq(&q->lock);
list_splice_init(&q->task_list, &tmp);
while (!list_empty(&tmp)) {
curr = list_first_entry(&tmp, typeof(*curr), task_list);
wake_up_state(curr->task, TASK_NORMAL);
list_del_init(&curr->task_list);
if (list_empty(&tmp))
break;
raw_spin_unlock_irq(&q->lock);
raw_spin_lock_irq(&q->lock);
}
raw_spin_unlock_irq(&q->lock);
}
EXPORT_SYMBOL(swake_up_all);
void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
{
wait->task = current;
if (list_empty(&wait->task_list))
list_add(&wait->task_list, &q->task_list);
}
void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state)
{
unsigned long flags;
raw_spin_lock_irqsave(&q->lock, flags);
__prepare_to_swait(q, wait);
set_current_state(state);
raw_spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(prepare_to_swait);
long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state)
{
if (signal_pending_state(state, current))
return -ERESTARTSYS;
prepare_to_swait(q, wait, state);
return 0;
}
EXPORT_SYMBOL(prepare_to_swait_event);
void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
{
__set_current_state(TASK_RUNNING);
if (!list_empty(&wait->task_list))
list_del_init(&wait->task_list);
}
void finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
{
unsigned long flags;
__set_current_state(TASK_RUNNING);
if (!list_empty_careful(&wait->task_list)) {
raw_spin_lock_irqsave(&q->lock, flags);
list_del_init(&wait->task_list);
raw_spin_unlock_irqrestore(&q->lock, flags);
}
}
EXPORT_SYMBOL(finish_swait);
|
