qemu-img: Omit error_report() after img_open()
[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 "block/coroutine.h"
27 #include "block/coroutine_int.h"
28 #include "qemu/queue.h"
29 #include "trace.h"
30
31 void qemu_co_queue_init(CoQueue *queue)
32 {
33 QTAILQ_INIT(&queue->entries);
34 }
35
36 void coroutine_fn qemu_co_queue_wait(CoQueue *queue)
37 {
38 Coroutine *self = qemu_coroutine_self();
39 QTAILQ_INSERT_TAIL(&queue->entries, self, co_queue_next);
40 qemu_coroutine_yield();
41 assert(qemu_in_coroutine());
42 }
43
44 /**
45 * qemu_co_queue_run_restart:
46 *
47 * Enter each coroutine that was previously marked for restart by
48 * qemu_co_queue_next() or qemu_co_queue_restart_all(). This function is
49 * invoked by the core coroutine code when the current coroutine yields or
50 * terminates.
51 */
52 void qemu_co_queue_run_restart(Coroutine *co)
53 {
54 Coroutine *next;
55
56 trace_qemu_co_queue_run_restart(co);
57 while ((next = QTAILQ_FIRST(&co->co_queue_wakeup))) {
58 QTAILQ_REMOVE(&co->co_queue_wakeup, next, co_queue_next);
59 qemu_coroutine_enter(next, NULL);
60 }
61 }
62
63 static bool qemu_co_queue_do_restart(CoQueue *queue, bool single)
64 {
65 Coroutine *self = qemu_coroutine_self();
66 Coroutine *next;
67
68 if (QTAILQ_EMPTY(&queue->entries)) {
69 return false;
70 }
71
72 while ((next = QTAILQ_FIRST(&queue->entries)) != NULL) {
73 QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
74 QTAILQ_INSERT_TAIL(&self->co_queue_wakeup, next, co_queue_next);
75 trace_qemu_co_queue_next(next);
76 if (single) {
77 break;
78 }
79 }
80 return true;
81 }
82
83 bool coroutine_fn qemu_co_queue_next(CoQueue *queue)
84 {
85 assert(qemu_in_coroutine());
86 return qemu_co_queue_do_restart(queue, true);
87 }
88
89 void coroutine_fn qemu_co_queue_restart_all(CoQueue *queue)
90 {
91 assert(qemu_in_coroutine());
92 qemu_co_queue_do_restart(queue, false);
93 }
94
95 bool qemu_co_enter_next(CoQueue *queue)
96 {
97 Coroutine *next;
98
99 next = QTAILQ_FIRST(&queue->entries);
100 if (!next) {
101 return false;
102 }
103
104 QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
105 qemu_coroutine_enter(next, NULL);
106 return true;
107 }
108
109 bool qemu_co_queue_empty(CoQueue *queue)
110 {
111 return (QTAILQ_FIRST(&queue->entries) == NULL);
112 }
113
114 void qemu_co_mutex_init(CoMutex *mutex)
115 {
116 memset(mutex, 0, sizeof(*mutex));
117 qemu_co_queue_init(&mutex->queue);
118 }
119
120 void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex)
121 {
122 Coroutine *self = qemu_coroutine_self();
123
124 trace_qemu_co_mutex_lock_entry(mutex, self);
125
126 while (mutex->locked) {
127 qemu_co_queue_wait(&mutex->queue);
128 }
129
130 mutex->locked = true;
131
132 trace_qemu_co_mutex_lock_return(mutex, self);
133 }
134
135 void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex)
136 {
137 Coroutine *self = qemu_coroutine_self();
138
139 trace_qemu_co_mutex_unlock_entry(mutex, self);
140
141 assert(mutex->locked == true);
142 assert(qemu_in_coroutine());
143
144 mutex->locked = false;
145 qemu_co_queue_next(&mutex->queue);
146
147 trace_qemu_co_mutex_unlock_return(mutex, self);
148 }
149
150 void qemu_co_rwlock_init(CoRwlock *lock)
151 {
152 memset(lock, 0, sizeof(*lock));
153 qemu_co_queue_init(&lock->queue);
154 }
155
156 void qemu_co_rwlock_rdlock(CoRwlock *lock)
157 {
158 while (lock->writer) {
159 qemu_co_queue_wait(&lock->queue);
160 }
161 lock->reader++;
162 }
163
164 void qemu_co_rwlock_unlock(CoRwlock *lock)
165 {
166 assert(qemu_in_coroutine());
167 if (lock->writer) {
168 lock->writer = false;
169 qemu_co_queue_restart_all(&lock->queue);
170 } else {
171 lock->reader--;
172 assert(lock->reader >= 0);
173 /* Wakeup only one waiting writer */
174 if (!lock->reader) {
175 qemu_co_queue_next(&lock->queue);
176 }
177 }
178 }
179
180 void qemu_co_rwlock_wrlock(CoRwlock *lock)
181 {
182 while (lock->writer || lock->reader) {
183 qemu_co_queue_wait(&lock->queue);
184 }
185 lock->writer = true;
186 }