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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
97fb7a0a IM |
2 | /* |
3 | * <linux/swait.h> (simple wait queues ) implementation: | |
4 | */ | |
325ea10c | 5 | #include "sched.h" |
13b35686 PZI |
6 | |
7 | void __init_swait_queue_head(struct swait_queue_head *q, const char *name, | |
8 | struct lock_class_key *key) | |
9 | { | |
10 | raw_spin_lock_init(&q->lock); | |
11 | lockdep_set_class_and_name(&q->lock, key, name); | |
12 | INIT_LIST_HEAD(&q->task_list); | |
13 | } | |
14 | EXPORT_SYMBOL(__init_swait_queue_head); | |
15 | ||
16 | /* | |
17 | * The thing about the wake_up_state() return value; I think we can ignore it. | |
18 | * | |
19 | * If for some reason it would return 0, that means the previously waiting | |
20 | * task is already running, so it will observe condition true (or has already). | |
21 | */ | |
22 | void swake_up_locked(struct swait_queue_head *q) | |
23 | { | |
24 | struct swait_queue *curr; | |
25 | ||
26 | if (list_empty(&q->task_list)) | |
27 | return; | |
28 | ||
29 | curr = list_first_entry(&q->task_list, typeof(*curr), task_list); | |
30 | wake_up_process(curr->task); | |
31 | list_del_init(&curr->task_list); | |
32 | } | |
33 | EXPORT_SYMBOL(swake_up_locked); | |
34 | ||
35 | void swake_up(struct swait_queue_head *q) | |
36 | { | |
37 | unsigned long flags; | |
38 | ||
13b35686 PZI |
39 | raw_spin_lock_irqsave(&q->lock, flags); |
40 | swake_up_locked(q); | |
41 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
42 | } | |
43 | EXPORT_SYMBOL(swake_up); | |
44 | ||
45 | /* | |
46 | * Does not allow usage from IRQ disabled, since we must be able to | |
47 | * release IRQs to guarantee bounded hold time. | |
48 | */ | |
49 | void swake_up_all(struct swait_queue_head *q) | |
50 | { | |
51 | struct swait_queue *curr; | |
52 | LIST_HEAD(tmp); | |
53 | ||
13b35686 PZI |
54 | raw_spin_lock_irq(&q->lock); |
55 | list_splice_init(&q->task_list, &tmp); | |
56 | while (!list_empty(&tmp)) { | |
57 | curr = list_first_entry(&tmp, typeof(*curr), task_list); | |
58 | ||
59 | wake_up_state(curr->task, TASK_NORMAL); | |
60 | list_del_init(&curr->task_list); | |
61 | ||
62 | if (list_empty(&tmp)) | |
63 | break; | |
64 | ||
65 | raw_spin_unlock_irq(&q->lock); | |
66 | raw_spin_lock_irq(&q->lock); | |
67 | } | |
68 | raw_spin_unlock_irq(&q->lock); | |
69 | } | |
70 | EXPORT_SYMBOL(swake_up_all); | |
71 | ||
72 | void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
73 | { | |
74 | wait->task = current; | |
75 | if (list_empty(&wait->task_list)) | |
76 | list_add(&wait->task_list, &q->task_list); | |
77 | } | |
78 | ||
79 | void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state) | |
80 | { | |
81 | unsigned long flags; | |
82 | ||
83 | raw_spin_lock_irqsave(&q->lock, flags); | |
84 | __prepare_to_swait(q, wait); | |
85 | set_current_state(state); | |
86 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
87 | } | |
88 | EXPORT_SYMBOL(prepare_to_swait); | |
89 | ||
90 | long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state) | |
91 | { | |
92 | if (signal_pending_state(state, current)) | |
93 | return -ERESTARTSYS; | |
94 | ||
95 | prepare_to_swait(q, wait, state); | |
96 | ||
97 | return 0; | |
98 | } | |
99 | EXPORT_SYMBOL(prepare_to_swait_event); | |
100 | ||
101 | void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
102 | { | |
103 | __set_current_state(TASK_RUNNING); | |
104 | if (!list_empty(&wait->task_list)) | |
105 | list_del_init(&wait->task_list); | |
106 | } | |
107 | ||
108 | void finish_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
109 | { | |
110 | unsigned long flags; | |
111 | ||
112 | __set_current_state(TASK_RUNNING); | |
113 | ||
114 | if (!list_empty_careful(&wait->task_list)) { | |
115 | raw_spin_lock_irqsave(&q->lock, flags); | |
116 | list_del_init(&wait->task_list); | |
117 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
118 | } | |
119 | } | |
120 | EXPORT_SYMBOL(finish_swait); |