iothread: release AioContext around aio_poll

This is the first step towards having fine-grained critical sections in
dataplane threads, which will resolve lock ordering problems between
address_space_* functions (which need the BQL when doing MMIO, even
after we complete RCU-based dispatch) and the AioContext.

Because AioContext does not use contention callbacks anymore, the
unit test has to be changed.

Previously applied as a0710f7995f914e3044e5899bd8ff6c43c62f916 and
then reverted.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-19-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>

1 files changed, 2 insertions, 9 deletions

diff --git a/iothread.c b/iothread.c
index fdfb440fc4..bd70344811 100644
--- a/iothread.c
+++ b/iothread.c
@@ -40,7 +40,6 @@ AioContext *qemu_get_current_aio_context(void)
 static void *iothread_run(void *opaque)
 {
     IOThread *iothread = opaque;
-    bool blocking;
 
     rcu_register_thread();
 
@@ -50,14 +49,8 @@ static void *iothread_run(void *opaque)
     qemu_cond_signal(&iothread->init_done_cond);
     qemu_mutex_unlock(&iothread->init_done_lock);
 
-    while (!iothread->stopping) {
-        aio_context_acquire(iothread->ctx);
-        blocking = true;
-        while (!iothread->stopping && aio_poll(iothread->ctx, blocking)) {
-            /* Progress was made, keep going */
-            blocking = false;
-        }
-        aio_context_release(iothread->ctx);
+    while (!atomic_read(&iothread->stopping)) {
+        aio_poll(iothread->ctx, true);
     }
 
     rcu_unregister_thread();