[PATCH] virtio-blk: don't start dataplane during the stop of dataplane

[<lv.mengzhao@zte.com.cn>]

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From: hujian <hu.jian@zte.com.cn>

During the stop of dataplane for virtio-blk, virtio_bus_cleanup_host_notifier() is be
called to clean up notifier at the end, if polled ioeventfd, virtio_blk_handle_output()
is used to handle io request. But due to s->dataplane_disabled is false, it will be
returned directly, which drops io request.
Backtrace:
->virtio_blk_data_plane_stop
  ->virtio_bus_cleanup_host_notifier
    ->virtio_queue_host_notifier_read
      ->virtio_queue_notify_vq
        ->vq->handle_output
          ->virtio_blk_handle_output
            ->if (s->dataplane  && !s->dataplane_stoped)
              ->if (!s->dataplane_disabled)
                ->return *
            ->virtio_blk_handle_output_do
The above problem can occur when using "virsh reset" cmdline to reset guest, while
guest does io.
To fix this problem, don't try to start dataplane if s->stopping is true, and io will
be handled by virtio_blk_handle_vq().

Signed-off-by: hujian <hu.jian@zte.com.cn>
---
 hw/block/virtio-blk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 39e7f23..c2d5938 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1166,7 +1166,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBlock *s = (VirtIOBlock *)vdev;

-    if (s->dataplane && !s->dataplane_started) {
+    if (s->dataplane && !s->dataplane_started && !s->stopping) {
         /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
          * dataplane here instead of waiting for .set_status().
          */
--
1.8.3.1

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