Merge branch 'for-upstream' of git://repo.or.cz/qemu/agraf
[qemu.git] / qemu-coroutine-lock.c
1 /*
2 * coroutine queues and locks
3 *
4 * Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 #include "qemu-common.h"
26 #include "qemu-coroutine.h"
27 #include "qemu-coroutine-int.h"
28 #include "qemu-queue.h"
29 #include "main-loop.h"
30 #include "trace.h"
31
32 static QTAILQ_HEAD(, Coroutine) unlock_bh_queue =
33 QTAILQ_HEAD_INITIALIZER(unlock_bh_queue);
34 static QEMUBH* unlock_bh;
35
36 static void qemu_co_queue_next_bh(void *opaque)
37 {
38 Coroutine *next;
39
40 trace_qemu_co_queue_next_bh();
41 while ((next = QTAILQ_FIRST(&unlock_bh_queue))) {
42 QTAILQ_REMOVE(&unlock_bh_queue, next, co_queue_next);
43 qemu_coroutine_enter(next, NULL);
44 }
45 }
46
47 void qemu_co_queue_init(CoQueue *queue)
48 {
49 QTAILQ_INIT(&queue->entries);
50
51 if (!unlock_bh) {
52 unlock_bh = qemu_bh_new(qemu_co_queue_next_bh, NULL);
53 }
54 }
55
56 void coroutine_fn qemu_co_queue_wait(CoQueue *queue)
57 {
58 Coroutine *self = qemu_coroutine_self();
59 QTAILQ_INSERT_TAIL(&queue->entries, self, co_queue_next);
60 qemu_coroutine_yield();
61 assert(qemu_in_coroutine());
62 }
63
64 void coroutine_fn qemu_co_queue_wait_insert_head(CoQueue *queue)
65 {
66 Coroutine *self = qemu_coroutine_self();
67 QTAILQ_INSERT_HEAD(&queue->entries, self, co_queue_next);
68 qemu_coroutine_yield();
69 assert(qemu_in_coroutine());
70 }
71
72 bool qemu_co_queue_next(CoQueue *queue)
73 {
74 Coroutine *next;
75
76 next = QTAILQ_FIRST(&queue->entries);
77 if (next) {
78 QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
79 QTAILQ_INSERT_TAIL(&unlock_bh_queue, next, co_queue_next);
80 trace_qemu_co_queue_next(next);
81 qemu_bh_schedule(unlock_bh);
82 }
83
84 return (next != NULL);
85 }
86
87 void qemu_co_queue_restart_all(CoQueue *queue)
88 {
89 while (qemu_co_queue_next(queue)) {
90 /* Do nothing */
91 }
92 }
93
94 bool qemu_co_queue_empty(CoQueue *queue)
95 {
96 return (QTAILQ_FIRST(&queue->entries) == NULL);
97 }
98
99 void qemu_co_mutex_init(CoMutex *mutex)
100 {
101 memset(mutex, 0, sizeof(*mutex));
102 qemu_co_queue_init(&mutex->queue);
103 }
104
105 void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex)
106 {
107 Coroutine *self = qemu_coroutine_self();
108
109 trace_qemu_co_mutex_lock_entry(mutex, self);
110
111 while (mutex->locked) {
112 qemu_co_queue_wait(&mutex->queue);
113 }
114
115 mutex->locked = true;
116
117 trace_qemu_co_mutex_lock_return(mutex, self);
118 }
119
120 void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex)
121 {
122 Coroutine *self = qemu_coroutine_self();
123
124 trace_qemu_co_mutex_unlock_entry(mutex, self);
125
126 assert(mutex->locked == true);
127 assert(qemu_in_coroutine());
128
129 mutex->locked = false;
130 qemu_co_queue_next(&mutex->queue);
131
132 trace_qemu_co_mutex_unlock_return(mutex, self);
133 }
134
135 void qemu_co_rwlock_init(CoRwlock *lock)
136 {
137 memset(lock, 0, sizeof(*lock));
138 qemu_co_queue_init(&lock->queue);
139 }
140
141 void qemu_co_rwlock_rdlock(CoRwlock *lock)
142 {
143 while (lock->writer) {
144 qemu_co_queue_wait(&lock->queue);
145 }
146 lock->reader++;
147 }
148
149 void qemu_co_rwlock_unlock(CoRwlock *lock)
150 {
151 assert(qemu_in_coroutine());
152 if (lock->writer) {
153 lock->writer = false;
154 qemu_co_queue_restart_all(&lock->queue);
155 } else {
156 lock->reader--;
157 assert(lock->reader >= 0);
158 /* Wakeup only one waiting writer */
159 if (!lock->reader) {
160 qemu_co_queue_next(&lock->queue);
161 }
162 }
163 }
164
165 void qemu_co_rwlock_wrlock(CoRwlock *lock)
166 {
167 while (lock->writer || lock->reader) {
168 qemu_co_queue_wait(&lock->queue);
169 }
170 lock->writer = true;
171 }