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/*
* QEMU coroutines
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
* Kevin Wolf <kwolf@redhat.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "trace.h"
#include "qemu-common.h"
#include "qemu/thread.h"
#include "block/coroutine.h"
#include "block/coroutine_int.h"
enum {
/* Maximum free pool size prevents holding too many freed coroutines */
POOL_MAX_SIZE = 64,
};
/** Free list to speed up creation */
static QemuMutex pool_lock;
static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
static unsigned int pool_size;
Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
{
Coroutine *co;
qemu_mutex_lock(&pool_lock);
co = QSLIST_FIRST(&pool);
if (co) {
QSLIST_REMOVE_HEAD(&pool, pool_next);
pool_size--;
}
qemu_mutex_unlock(&pool_lock);
if (!co) {
co = qemu_coroutine_new();
}
co->entry = entry;
QTAILQ_INIT(&co->co_queue_wakeup);
return co;
}
static void coroutine_delete(Coroutine *co)
{
qemu_mutex_lock(&pool_lock);
if (pool_size < POOL_MAX_SIZE) {
QSLIST_INSERT_HEAD(&pool, co, pool_next);
co->caller = NULL;
pool_size++;
qemu_mutex_unlock(&pool_lock);
return;
}
qemu_mutex_unlock(&pool_lock);
qemu_coroutine_delete(co);
}
static void __attribute__((constructor)) coroutine_pool_init(void)
{
qemu_mutex_init(&pool_lock);
}
static void __attribute__((destructor)) coroutine_pool_cleanup(void)
{
Coroutine *co;
Coroutine *tmp;
QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) {
QSLIST_REMOVE_HEAD(&pool, pool_next);
qemu_coroutine_delete(co);
}
qemu_mutex_destroy(&pool_lock);
}
static void coroutine_swap(Coroutine *from, Coroutine *to)
{
CoroutineAction ret;
ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);
qemu_co_queue_run_restart(to);
switch (ret) {
case COROUTINE_YIELD:
return;
case COROUTINE_TERMINATE:
trace_qemu_coroutine_terminate(to);
coroutine_delete(to);
return;
default:
abort();
}
}
void qemu_coroutine_enter(Coroutine *co, void *opaque)
{
Coroutine *self = qemu_coroutine_self();
trace_qemu_coroutine_enter(self, co, opaque);
if (co->caller) {
fprintf(stderr, "Co-routine re-entered recursively\n");
abort();
}
co->caller = self;
co->entry_arg = opaque;
coroutine_swap(self, co);
}
void coroutine_fn qemu_coroutine_yield(void)
{
Coroutine *self = qemu_coroutine_self();
Coroutine *to = self->caller;
trace_qemu_coroutine_yield(self, to);
if (!to) {
fprintf(stderr, "Co-routine is yielding to no one\n");
abort();
}
self->caller = NULL;
coroutine_swap(self, to);
}
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