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/*
* 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 "block/aio.h"
#include "trace.h"
/* Coroutines are awoken from a BH to allow the current coroutine to complete
* its flow of execution. The BH may run after the CoQueue has been destroyed,
* so keep BH data in a separate heap-allocated struct.
*/
typedef struct {
QEMUBH *bh;
QTAILQ_HEAD(, Coroutine) entries;
} CoQueueNextData;
static void qemu_co_queue_next_bh(void *opaque)
{
CoQueueNextData *data = opaque;
Coroutine *next;
trace_qemu_co_queue_next_bh();
while ((next = QTAILQ_FIRST(&data->entries))) {
QTAILQ_REMOVE(&data->entries, next, co_queue_next);
qemu_coroutine_enter(next, NULL);
}
qemu_bh_delete(data->bh);
g_slice_free(CoQueueNextData, data);
}
void qemu_co_queue_init(CoQueue *queue)
{
QTAILQ_INIT(&queue->entries);
/* This will be exposed to callers once there are multiple AioContexts */
queue->ctx = qemu_get_aio_context();
}
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());
}
void coroutine_fn qemu_co_queue_wait_insert_head(CoQueue *queue)
{
Coroutine *self = qemu_coroutine_self();
QTAILQ_INSERT_HEAD(&queue->entries, self, co_queue_next);
qemu_coroutine_yield();
assert(qemu_in_coroutine());
}
static bool qemu_co_queue_do_restart(CoQueue *queue, bool single)
{
Coroutine *next;
CoQueueNextData *data;
if (QTAILQ_EMPTY(&queue->entries)) {
return false;
}
data = g_slice_new(CoQueueNextData);
data->bh = aio_bh_new(queue->ctx, qemu_co_queue_next_bh, data);
QTAILQ_INIT(&data->entries);
qemu_bh_schedule(data->bh);
while ((next = QTAILQ_FIRST(&queue->entries)) != NULL) {
QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
QTAILQ_INSERT_TAIL(&data->entries, next, co_queue_next);
trace_qemu_co_queue_next(next);
if (single) {
break;
}
}
return true;
}
bool qemu_co_queue_next(CoQueue *queue)
{
return qemu_co_queue_do_restart(queue, true);
}
void qemu_co_queue_restart_all(CoQueue *queue)
{
qemu_co_queue_do_restart(queue, false);
}
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;
}
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