@@ -229,6 +229,22 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
return -ENOSYS;
}
+/* Stop notifications for new requests from guest.
+ *
+ * Context: BH in IOThread
+ */
+static void virtio_blk_data_plane_stop_bh(void *opaque)
+{
+ VirtIOBlockDataPlane *s = opaque;
+ unsigned i;
+
+ for (i = 0; i < s->conf->num_queues; i++) {
+ VirtQueue *vq = virtio_get_queue(s->vdev, i);
+
+ virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, NULL);
+ }
+}
+
/* Context: QEMU global mutex held */
void virtio_blk_data_plane_stop(VirtIODevice *vdev)
{
@@ -253,13 +269,7 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
trace_virtio_blk_data_plane_stop(s);
aio_context_acquire(s->ctx);
-
- /* Stop notifications for new requests from guest */
- for (i = 0; i < nvqs; i++) {
- VirtQueue *vq = virtio_get_queue(s->vdev, i);
-
- virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, NULL);
- }
+ aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s);
/* Drain and switch bs back to the QEMU main loop */
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
If the main loop thread invokes .ioeventfd_stop() just as the vq handler function begins in the IOThread then the handler may lose the race for the AioContext lock. By the time the vq handler is able to acquire the AioContext lock the ioeventfd has already been removed and the handler isn't supposed to run anymore! Use the new aio_wait_bh_oneshot() function to perform ioeventfd removal from within the IOThread. This way no races with the vq handler are possible. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- hw/block/dataplane/virtio-blk.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-)