virtio-scsi: don't process IO on fenced dataplane

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>
Message-Id: <20201217150040.906961-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index 2c83a0ab1f80ff7babb61364392f06786f76a426..4ad879340645b79b0d4c7f27e45d7c68b483242e 100644 (file)
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -52,12 +52,14 @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
 static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
                                               VirtQueue *vq)
 {
-    bool progress;
+    bool progress = false;
     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;
 }
@@ -65,12 +67,14 @@ static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
 static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
                                                VirtQueue *vq)
 {
-    bool progress;
+    bool progress = false;
     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;
 }
@@ -78,12 +82,14 @@ static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
 static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
                                                 VirtQueue *vq)
 {
-    bool progress;
+    bool progress = false;
     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;
 }