[PATCH 1/3] scsi: virtio-scsi: don't process IO on fenced dataplane

[Maxim Levitsky]

If virtio_scsi_dataplane_start fails, there is a small window when it drops the
aio lock (in aio_wait_bh_oneshot) and the dataplane's AIO handler can
still run during that window.

This is done after the dataplane was marked as fenced, thus we use this flag
to avoid it doing any IO.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 hw/scsi/virtio-scsi-dataplane.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index b995bab3a2..2824a25b65 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -56,8 +56,10 @@ static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice 
*vdev,
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 
     virtio_scsi_acquire(s);
-    assert(s->ctx && s->dataplane_started);
-    progress = virtio_scsi_handle_cmd_vq(s, vq);
+    if (!s->dataplane_fenced) {
+        assert(s->ctx && s->dataplane_started);
+        progress = virtio_scsi_handle_cmd_vq(s, vq);
+    }
     virtio_scsi_release(s);
     return progress;
 }
@@ -69,8 +71,10 @@ static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice 
*vdev,
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 
     virtio_scsi_acquire(s);
-    assert(s->ctx && s->dataplane_started);
-    progress = virtio_scsi_handle_ctrl_vq(s, vq);
+    if (!s->dataplane_fenced) {
+        assert(s->ctx && s->dataplane_started);
+        progress = virtio_scsi_handle_ctrl_vq(s, vq);
+    }
     virtio_scsi_release(s);
     return progress;
 }
@@ -82,8 +86,10 @@ static bool virtio_scsi_data_plane_handle_event(VirtIODevice 
*vdev,
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 
     virtio_scsi_acquire(s);
-    assert(s->ctx && s->dataplane_started);
-    progress = virtio_scsi_handle_event_vq(s, vq);
+    if (!s->dataplane_fenced) {
+        assert(s->ctx && s->dataplane_started);
+        progress = virtio_scsi_handle_event_vq(s, vq);
+    }
     virtio_scsi_release(s);
     return progress;
 }
-- 
2.26.2