On 29/03/2016 16:09, Michael S. Tsirkin wrote: >> > Another small comment, this can be written simply as >> > >> > if (s->dataplane) { >> > virtio_blk_data_plane_start(s->dataplane); > > True, it's best not to poke at dataplane_started. > > > } else { > > virtio_blk_handle_vq(s, vq); > > } > > > > I prefer the return style I think, to stress the > fact that this is an unusual, unexpected case.
We're getting dangerously close to personal preference, but I've noticed virtio-scsi that you get a very common pattern of: void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq) { ... virtqueue_pop ... } static void virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) { VirtIOSCSI *s = VIRTIO_SCSI(vdev); assert(dataplane active and started); virtio_scsi_handle_ctrl_vq(s, vq); } static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) { VirtIOSCSI *s = VIRTIO_SCSI(vdev); if (dataplane active) { virtio_scsi_dataplane_start(s); } else { virtio_scsi_handle_ctrl_vq(s, vq); } } so it's not really an unusual, unexpected case but a complete separation between the dataplane case (handle_output starts dataplane) and the non-dataplane case (handle_output just does a cast and calls the actual workhorse). Paolo