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