1 /*
2 * Copyright (c) 2019-2020 François Tigeot <ftigeot@wolfpond.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include <linux/wait.h>
28 #include <linux/wait_bit.h>
29 #include <linux/sched.h>
30
31 int
default_wake_function(wait_queue_entry_t * q,unsigned mode,int wake_flags,void * key)32 default_wake_function(wait_queue_entry_t *q, unsigned mode, int wake_flags, void *key)
33 {
34 return wake_up_process(q->private);
35 }
36
37 int
autoremove_wake_function(wait_queue_entry_t * wait,unsigned mode,int sync,void * key)38 autoremove_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
39 {
40 int ret = default_wake_function(wait, mode, sync, key);
41
42 /* Was the process woken up ? */
43 if (ret)
44 list_del_init(&wait->entry);
45
46 return ret;
47 }
48
49 void
__wake_up_core(wait_queue_head_t * q,int num_to_wake_up)50 __wake_up_core(wait_queue_head_t *q, int num_to_wake_up)
51 {
52 wait_queue_entry_t *curr, *next;
53 int mode = TASK_NORMAL;
54
55 list_for_each_entry_safe(curr, next, &q->head, entry) {
56 if (curr->func(curr, mode, 0, NULL))
57 num_to_wake_up--;
58
59 if (num_to_wake_up == 0)
60 break;
61 }
62 }
63
64 void
__wait_event_prefix(wait_queue_head_t * wq,int flags)65 __wait_event_prefix(wait_queue_head_t *wq, int flags)
66 {
67 lockmgr(&wq->lock, LK_EXCLUSIVE);
68 if (flags & PCATCH) {
69 set_current_state(TASK_INTERRUPTIBLE);
70 } else {
71 set_current_state(TASK_UNINTERRUPTIBLE);
72 }
73 lockmgr(&wq->lock, LK_RELEASE);
74 }
75
76 void
prepare_to_wait(wait_queue_head_t * q,wait_queue_entry_t * wait,int state)77 prepare_to_wait(wait_queue_head_t *q, wait_queue_entry_t *wait, int state)
78 {
79 lockmgr(&q->lock, LK_EXCLUSIVE);
80 if (list_empty(&wait->entry))
81 __add_wait_queue(q, wait);
82 set_current_state(state);
83 lockmgr(&q->lock, LK_RELEASE);
84 }
85
86 void
finish_wait(wait_queue_head_t * q,wait_queue_entry_t * wait)87 finish_wait(wait_queue_head_t *q, wait_queue_entry_t *wait)
88 {
89 set_current_state(TASK_RUNNING);
90
91 lockmgr(&q->lock, LK_EXCLUSIVE);
92 if (!list_empty(&wait->entry))
93 list_del_init(&wait->entry);
94 lockmgr(&q->lock, LK_RELEASE);
95 }
96
97 void
wake_up_bit(void * addr,int bit)98 wake_up_bit(void *addr, int bit)
99 {
100 wakeup_one(addr);
101 }
102
103 /* Wait for a bit to be cleared or a timeout to expire */
104 int
wait_on_bit_timeout(unsigned long * word,int bit,unsigned mode,unsigned long timeout)105 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
106 unsigned long timeout)
107 {
108 int rv, awakened = 0, timeout_expired = 0;
109 long start_time;
110
111 if (!test_bit(bit, word))
112 return 0;
113
114 start_time = ticks;
115 set_current_state(mode);
116
117 do {
118 rv = tsleep(word, mode, "lwobt", timeout);
119 if (rv == 0)
120 awakened = 1;
121 if (time_after_eq(start_time, timeout))
122 timeout_expired = 1;
123 } while (test_bit(bit, word) && !timeout_expired);
124
125 set_current_state(TASK_RUNNING);
126
127 if (awakened)
128 return 0;
129
130 return 1;
131 }
132
__init_waitqueue_head(wait_queue_head_t * q,const char * name,struct lock_class_key * key)133 void __init_waitqueue_head(wait_queue_head_t *q,
134 const char *name, struct lock_class_key *key)
135 {
136 lockinit(&q->lock, "lwq", 0, 0);
137 INIT_LIST_HEAD(&q->head);
138 }
139
140 int
wait_on_bit(unsigned long * word,int bit,unsigned mode)141 wait_on_bit(unsigned long *word, int bit, unsigned mode)
142 {
143 return wait_on_bit_timeout(word, bit, mode, MAX_SCHEDULE_TIMEOUT);
144 }
145
146 void
init_wait_entry(struct wait_queue_entry * wq_entry,int flags)147 init_wait_entry(struct wait_queue_entry *wq_entry, int flags)
148 {
149 INIT_LIST_HEAD(&wq_entry->entry);
150 wq_entry->flags = flags;
151 wq_entry->private = current;
152 wq_entry->func = autoremove_wake_function;
153 }
154