aboutsummaryrefslogtreecommitdiff
path: root/qemu-coroutine-lock.c
blob: e4860ae42f7713b74f568ccf0c1310f7d632a08e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
/*
 * coroutine queues and locks
 *
 * Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu-common.h"
#include "block/coroutine.h"
#include "block/coroutine_int.h"
#include "qemu/queue.h"
#include "trace.h"

void qemu_co_queue_init(CoQueue *queue)
{
    QTAILQ_INIT(&queue->entries);
}

void coroutine_fn qemu_co_queue_wait(CoQueue *queue)
{
    Coroutine *self = qemu_coroutine_self();
    QTAILQ_INSERT_TAIL(&queue->entries, self, co_queue_next);
    qemu_coroutine_yield();
    assert(qemu_in_coroutine());
}

/**
 * qemu_co_queue_run_restart:
 *
 * Enter each coroutine that was previously marked for restart by
 * qemu_co_queue_next() or qemu_co_queue_restart_all().  This function is
 * invoked by the core coroutine code when the current coroutine yields or
 * terminates.
 */
void qemu_co_queue_run_restart(Coroutine *co)
{
    Coroutine *next;

    trace_qemu_co_queue_run_restart(co);
    while ((next = QTAILQ_FIRST(&co->co_queue_wakeup))) {
        QTAILQ_REMOVE(&co->co_queue_wakeup, next, co_queue_next);
        qemu_coroutine_enter(next, NULL);
    }
}

static bool qemu_co_queue_do_restart(CoQueue *queue, bool single)
{
    Coroutine *self = qemu_coroutine_self();
    Coroutine *next;

    if (QTAILQ_EMPTY(&queue->entries)) {
        return false;
    }

    while ((next = QTAILQ_FIRST(&queue->entries)) != NULL) {
        QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
        QTAILQ_INSERT_TAIL(&self->co_queue_wakeup, next, co_queue_next);
        trace_qemu_co_queue_next(next);
        if (single) {
            break;
        }
    }
    return true;
}

bool coroutine_fn qemu_co_queue_next(CoQueue *queue)
{
    assert(qemu_in_coroutine());
    return qemu_co_queue_do_restart(queue, true);
}

void coroutine_fn qemu_co_queue_restart_all(CoQueue *queue)
{
    assert(qemu_in_coroutine());
    qemu_co_queue_do_restart(queue, false);
}

bool qemu_co_enter_next(CoQueue *queue)
{
    Coroutine *next;

    next = QTAILQ_FIRST(&queue->entries);
    if (!next) {
        return false;
    }

    QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
    qemu_coroutine_enter(next, NULL);
    return true;
}

bool qemu_co_queue_empty(CoQueue *queue)
{
    return (QTAILQ_FIRST(&queue->entries) == NULL);
}

void qemu_co_mutex_init(CoMutex *mutex)
{
    memset(mutex, 0, sizeof(*mutex));
    qemu_co_queue_init(&mutex->queue);
}

void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex)
{
    Coroutine *self = qemu_coroutine_self();

    trace_qemu_co_mutex_lock_entry(mutex, self);

    while (mutex->locked) {
        qemu_co_queue_wait(&mutex->queue);
    }

    mutex->locked = true;

    trace_qemu_co_mutex_lock_return(mutex, self);
}

void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex)
{
    Coroutine *self = qemu_coroutine_self();

    trace_qemu_co_mutex_unlock_entry(mutex, self);

    assert(mutex->locked == true);
    assert(qemu_in_coroutine());

    mutex->locked = false;
    qemu_co_queue_next(&mutex->queue);

    trace_qemu_co_mutex_unlock_return(mutex, self);
}

void qemu_co_rwlock_init(CoRwlock *lock)
{
    memset(lock, 0, sizeof(*lock));
    qemu_co_queue_init(&lock->queue);
}

void qemu_co_rwlock_rdlock(CoRwlock *lock)
{
    while (lock->writer) {
        qemu_co_queue_wait(&lock->queue);
    }
    lock->reader++;
}

void qemu_co_rwlock_unlock(CoRwlock *lock)
{
    assert(qemu_in_coroutine());
    if (lock->writer) {
        lock->writer = false;
        qemu_co_queue_restart_all(&lock->queue);
    } else {
        lock->reader--;
        assert(lock->reader >= 0);
        /* Wakeup only one waiting writer */
        if (!lock->reader) {
            qemu_co_queue_next(&lock->queue);
        }
    }
}

void qemu_co_rwlock_wrlock(CoRwlock *lock)
{
    while (lock->writer || lock->reader) {
        qemu_co_queue_wait(&lock->queue);
    }
    lock->writer = true;
}