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-rw-r--r--qemu/util/qemu-coroutine.c147
1 files changed, 147 insertions, 0 deletions
diff --git a/qemu/util/qemu-coroutine.c b/qemu/util/qemu-coroutine.c
new file mode 100644
index 000000000..5816702cc
--- /dev/null
+++ b/qemu/util/qemu-coroutine.c
@@ -0,0 +1,147 @@
+/*
+ * 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 "qemu/osdep.h"
+#include "trace.h"
+#include "qemu-common.h"
+#include "qemu/thread.h"
+#include "qemu/atomic.h"
+#include "qemu/coroutine.h"
+#include "qemu/coroutine_int.h"
+
+enum {
+ POOL_BATCH_SIZE = 64,
+};
+
+/** Free list to speed up creation */
+static QSLIST_HEAD(, Coroutine) release_pool = QSLIST_HEAD_INITIALIZER(pool);
+static unsigned int release_pool_size;
+static __thread QSLIST_HEAD(, Coroutine) alloc_pool = QSLIST_HEAD_INITIALIZER(pool);
+static __thread unsigned int alloc_pool_size;
+static __thread Notifier coroutine_pool_cleanup_notifier;
+
+static void coroutine_pool_cleanup(Notifier *n, void *value)
+{
+ Coroutine *co;
+ Coroutine *tmp;
+
+ QSLIST_FOREACH_SAFE(co, &alloc_pool, pool_next, tmp) {
+ QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
+ qemu_coroutine_delete(co);
+ }
+}
+
+Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
+{
+ Coroutine *co = NULL;
+
+ if (CONFIG_COROUTINE_POOL) {
+ co = QSLIST_FIRST(&alloc_pool);
+ if (!co) {
+ if (release_pool_size > POOL_BATCH_SIZE) {
+ /* Slow path; a good place to register the destructor, too. */
+ if (!coroutine_pool_cleanup_notifier.notify) {
+ coroutine_pool_cleanup_notifier.notify = coroutine_pool_cleanup;
+ qemu_thread_atexit_add(&coroutine_pool_cleanup_notifier);
+ }
+
+ /* This is not exact; there could be a little skew between
+ * release_pool_size and the actual size of release_pool. But
+ * it is just a heuristic, it does not need to be perfect.
+ */
+ alloc_pool_size = atomic_xchg(&release_pool_size, 0);
+ QSLIST_MOVE_ATOMIC(&alloc_pool, &release_pool);
+ co = QSLIST_FIRST(&alloc_pool);
+ }
+ }
+ if (co) {
+ QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
+ alloc_pool_size--;
+ }
+ }
+
+ if (!co) {
+ co = qemu_coroutine_new();
+ }
+
+ co->entry = entry;
+ QTAILQ_INIT(&co->co_queue_wakeup);
+ return co;
+}
+
+static void coroutine_delete(Coroutine *co)
+{
+ co->caller = NULL;
+
+ if (CONFIG_COROUTINE_POOL) {
+ if (release_pool_size < POOL_BATCH_SIZE * 2) {
+ QSLIST_INSERT_HEAD_ATOMIC(&release_pool, co, pool_next);
+ atomic_inc(&release_pool_size);
+ return;
+ }
+ if (alloc_pool_size < POOL_BATCH_SIZE) {
+ QSLIST_INSERT_HEAD(&alloc_pool, co, pool_next);
+ alloc_pool_size++;
+ return;
+ }
+ }
+
+ qemu_coroutine_delete(co);
+}
+
+void qemu_coroutine_enter(Coroutine *co, void *opaque)
+{
+ Coroutine *self = qemu_coroutine_self();
+ CoroutineAction ret;
+
+ 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;
+ ret = qemu_coroutine_switch(self, co, COROUTINE_ENTER);
+
+ qemu_co_queue_run_restart(co);
+
+ switch (ret) {
+ case COROUTINE_YIELD:
+ return;
+ case COROUTINE_TERMINATE:
+ trace_qemu_coroutine_terminate(co);
+ coroutine_delete(co);
+ return;
+ default:
+ abort();
+ }
+}
+
+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;
+ qemu_coroutine_switch(self, to, COROUTINE_YIELD);
+}