Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
97fb7a0a IM |
2 | /* |
3 | * <linux/swait.h> (simple wait queues ) implementation: | |
4 | */ | |
13b35686 PZI |
5 | |
6 | void __init_swait_queue_head(struct swait_queue_head *q, const char *name, | |
7 | struct lock_class_key *key) | |
8 | { | |
9 | raw_spin_lock_init(&q->lock); | |
10 | lockdep_set_class_and_name(&q->lock, key, name); | |
11 | INIT_LIST_HEAD(&q->task_list); | |
12 | } | |
13 | EXPORT_SYMBOL(__init_swait_queue_head); | |
14 | ||
15 | /* | |
16 | * The thing about the wake_up_state() return value; I think we can ignore it. | |
17 | * | |
18 | * If for some reason it would return 0, that means the previously waiting | |
19 | * task is already running, so it will observe condition true (or has already). | |
20 | */ | |
21 | void swake_up_locked(struct swait_queue_head *q) | |
22 | { | |
23 | struct swait_queue *curr; | |
24 | ||
25 | if (list_empty(&q->task_list)) | |
26 | return; | |
27 | ||
28 | curr = list_first_entry(&q->task_list, typeof(*curr), task_list); | |
29 | wake_up_process(curr->task); | |
30 | list_del_init(&curr->task_list); | |
31 | } | |
32 | EXPORT_SYMBOL(swake_up_locked); | |
33 | ||
b3212fe2 TG |
34 | /* |
35 | * Wake up all waiters. This is an interface which is solely exposed for | |
36 | * completions and not for general usage. | |
37 | * | |
38 | * It is intentionally different from swake_up_all() to allow usage from | |
39 | * hard interrupt context and interrupt disabled regions. | |
40 | */ | |
41 | void swake_up_all_locked(struct swait_queue_head *q) | |
42 | { | |
43 | while (!list_empty(&q->task_list)) | |
44 | swake_up_locked(q); | |
45 | } | |
46 | ||
b3dae109 | 47 | void swake_up_one(struct swait_queue_head *q) |
13b35686 PZI |
48 | { |
49 | unsigned long flags; | |
50 | ||
13b35686 PZI |
51 | raw_spin_lock_irqsave(&q->lock, flags); |
52 | swake_up_locked(q); | |
53 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
54 | } | |
b3dae109 | 55 | EXPORT_SYMBOL(swake_up_one); |
13b35686 PZI |
56 | |
57 | /* | |
58 | * Does not allow usage from IRQ disabled, since we must be able to | |
59 | * release IRQs to guarantee bounded hold time. | |
60 | */ | |
61 | void swake_up_all(struct swait_queue_head *q) | |
62 | { | |
63 | struct swait_queue *curr; | |
64 | LIST_HEAD(tmp); | |
65 | ||
13b35686 PZI |
66 | raw_spin_lock_irq(&q->lock); |
67 | list_splice_init(&q->task_list, &tmp); | |
68 | while (!list_empty(&tmp)) { | |
69 | curr = list_first_entry(&tmp, typeof(*curr), task_list); | |
70 | ||
71 | wake_up_state(curr->task, TASK_NORMAL); | |
72 | list_del_init(&curr->task_list); | |
73 | ||
74 | if (list_empty(&tmp)) | |
75 | break; | |
76 | ||
77 | raw_spin_unlock_irq(&q->lock); | |
78 | raw_spin_lock_irq(&q->lock); | |
79 | } | |
80 | raw_spin_unlock_irq(&q->lock); | |
81 | } | |
82 | EXPORT_SYMBOL(swake_up_all); | |
83 | ||
b3212fe2 | 84 | void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait) |
13b35686 PZI |
85 | { |
86 | wait->task = current; | |
87 | if (list_empty(&wait->task_list)) | |
0abf17bc | 88 | list_add_tail(&wait->task_list, &q->task_list); |
13b35686 PZI |
89 | } |
90 | ||
b3dae109 | 91 | void prepare_to_swait_exclusive(struct swait_queue_head *q, struct swait_queue *wait, int state) |
13b35686 PZI |
92 | { |
93 | unsigned long flags; | |
94 | ||
95 | raw_spin_lock_irqsave(&q->lock, flags); | |
96 | __prepare_to_swait(q, wait); | |
97 | set_current_state(state); | |
98 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
99 | } | |
b3dae109 | 100 | EXPORT_SYMBOL(prepare_to_swait_exclusive); |
13b35686 PZI |
101 | |
102 | long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state) | |
103 | { | |
0abf17bc PZ |
104 | unsigned long flags; |
105 | long ret = 0; | |
13b35686 | 106 | |
0abf17bc | 107 | raw_spin_lock_irqsave(&q->lock, flags); |
34ec35ad | 108 | if (signal_pending_state(state, current)) { |
0abf17bc | 109 | /* |
b3dae109 | 110 | * See prepare_to_wait_event(). TL;DR, subsequent swake_up_one() |
0abf17bc PZ |
111 | * must not see us. |
112 | */ | |
113 | list_del_init(&wait->task_list); | |
114 | ret = -ERESTARTSYS; | |
115 | } else { | |
116 | __prepare_to_swait(q, wait); | |
117 | set_current_state(state); | |
118 | } | |
119 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
13b35686 | 120 | |
0abf17bc | 121 | return ret; |
13b35686 PZI |
122 | } |
123 | EXPORT_SYMBOL(prepare_to_swait_event); | |
124 | ||
125 | void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
126 | { | |
127 | __set_current_state(TASK_RUNNING); | |
128 | if (!list_empty(&wait->task_list)) | |
129 | list_del_init(&wait->task_list); | |
130 | } | |
131 | ||
132 | void finish_swait(struct swait_queue_head *q, struct swait_queue *wait) | |
133 | { | |
134 | unsigned long flags; | |
135 | ||
136 | __set_current_state(TASK_RUNNING); | |
137 | ||
138 | if (!list_empty_careful(&wait->task_list)) { | |
139 | raw_spin_lock_irqsave(&q->lock, flags); | |
140 | list_del_init(&wait->task_list); | |
141 | raw_spin_unlock_irqrestore(&q->lock, flags); | |
142 | } | |
143 | } | |
144 | EXPORT_SYMBOL(finish_swait); |