Revert "iothread: release iothread around aio_poll"

This reverts commit a0710f7995f914e3044e5899bd8ff6c43c62f916.

In qemu-devel email message <556DBF87.2020908@de.ibm.com>, Christian
Borntraeger writes:

  Having many guests all with a kernel/ramdisk (via -kernel) and
  several null block devices will result in hangs. All hanging
  guests are in partition detection code waiting for an I/O to return
  so very early maybe even the first I/O.

  Reverting that commit "fixes" the hangs.

Reverting this commit for the 2.4 release.  More time is needed to
investigate and correct this patch.

Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/iothread.c b/iothread.c
index 0416fc4..878a594 100644
--- a/iothread.c
+++ b/iothread.c
@@ -31,14 +31,21 @@ typedef ObjectClass IOThreadClass;
 static void *iothread_run(void *opaque)
 {
     IOThread *iothread = opaque;
+    bool blocking;
 
     qemu_mutex_lock(&iothread->init_done_lock);
     iothread->thread_id = qemu_get_thread_id();
     qemu_cond_signal(&iothread->init_done_cond);
     qemu_mutex_unlock(&iothread->init_done_lock);
 
-    while (!atomic_read(&iothread->stopping)) {
-        aio_poll(iothread->ctx, true);
+    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);
     }
     return NULL;
 }