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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
97fb7a0a IM |
2 | /* |
3 | * <linux/swait.h> (simple wait queues ) implementation: | |
4 | */ | |
174cd4b1 | 5 | #include <linux/sched/signal.h> |
13b35686 PZI |
6 | #include <linux/swait.h> |
7 | ||
8 | void __init_swait_queue_head(struct swait_queue_head *q, const char *name, | |
9 | struct lock_class_key *key) | |
10 | { | |
11 | raw_spin_lock_init(&q->lock); | |
12 | lockdep_set_class_and_name(&q->lock, key, name); | |
13 | INIT_LIST_HEAD(&q->task_list); | |
14 | } | |
15 | EXPORT_SYMBOL(__init_swait_queue_head); | |
16 | ||
17 | /* | |
18 | * The thing about the wake_up_state() return value; I think we can ignore it. | |
19 | * | |
20 | * If for some reason it would return 0, that means the previously waiting | |
21 | * task is already running, so it will observe condition true (or has already). | |
22 | */ | |
23 | void swake_up_locked(struct swait_queue_head *q) | |
24 | { | |
25 | struct swait_queue *curr; | |
26 | ||
27 | if (list_empty(&q->task_list)) | |
28 | return; | |
29 | ||
30 | curr = list_first_entry(&q->task_list, typeof(*curr), task_list); | |
31 | wake_up_process(curr->task); | |
32 | list_del_init(&curr->task_list); | |
33 | } | |
34 | EXPORT_SYMBOL(swake_up_locked); | |
35 | ||
36 | void swake_up(struct swait_queue_head *q) | |
37 | { | |
38 | unsigned long flags; | |
39 | ||
13b35686 PZI |
40 | raw_spin_lock_irqsave(&q->lock, flags); |
41 | swake_up_locked(q); | |
42 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
43 | } | |
44 | EXPORT_SYMBOL(swake_up); | |
45 | ||
46 | /* | |
47 | * Does not allow usage from IRQ disabled, since we must be able to | |
48 | * release IRQs to guarantee bounded hold time. | |
49 | */ | |
50 | void swake_up_all(struct swait_queue_head *q) | |
51 | { | |
52 | struct swait_queue *curr; | |
53 | LIST_HEAD(tmp); | |
54 | ||
13b35686 PZI |
55 | raw_spin_lock_irq(&q->lock); |
56 | list_splice_init(&q->task_list, &tmp); | |
57 | while (!list_empty(&tmp)) { | |
58 | curr = list_first_entry(&tmp, typeof(*curr), task_list); | |
59 | ||
60 | wake_up_state(curr->task, TASK_NORMAL); | |
61 | list_del_init(&curr->task_list); | |
62 | ||
63 | if (list_empty(&tmp)) | |
64 | break; | |
65 | ||
66 | raw_spin_unlock_irq(&q->lock); | |
67 | raw_spin_lock_irq(&q->lock); | |
68 | } | |
69 | raw_spin_unlock_irq(&q->lock); | |
70 | } | |
71 | EXPORT_SYMBOL(swake_up_all); | |
72 | ||
73 | void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
74 | { | |
75 | wait->task = current; | |
76 | if (list_empty(&wait->task_list)) | |
77 | list_add(&wait->task_list, &q->task_list); | |
78 | } | |
79 | ||
80 | void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state) | |
81 | { | |
82 | unsigned long flags; | |
83 | ||
84 | raw_spin_lock_irqsave(&q->lock, flags); | |
85 | __prepare_to_swait(q, wait); | |
86 | set_current_state(state); | |
87 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
88 | } | |
89 | EXPORT_SYMBOL(prepare_to_swait); | |
90 | ||
91 | long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state) | |
92 | { | |
93 | if (signal_pending_state(state, current)) | |
94 | return -ERESTARTSYS; | |
95 | ||
96 | prepare_to_swait(q, wait, state); | |
97 | ||
98 | return 0; | |
99 | } | |
100 | EXPORT_SYMBOL(prepare_to_swait_event); | |
101 | ||
102 | void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
103 | { | |
104 | __set_current_state(TASK_RUNNING); | |
105 | if (!list_empty(&wait->task_list)) | |
106 | list_del_init(&wait->task_list); | |
107 | } | |
108 | ||
109 | void finish_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
110 | { | |
111 | unsigned long flags; | |
112 | ||
113 | __set_current_state(TASK_RUNNING); | |
114 | ||
115 | if (!list_empty_careful(&wait->task_list)) { | |
116 | raw_spin_lock_irqsave(&q->lock, flags); | |
117 | list_del_init(&wait->task_list); | |
118 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
119 | } | |
120 | } | |
121 | EXPORT_SYMBOL(finish_swait); |