void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
{
	if (vif->tx.sring)
		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
					vif->tx.sring);
	if (vif->rx.sring)
		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
					vif->rx.sring);
}
void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
{
	if (vif->tx.sring)
		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
					vif->tx.sring);
	if (vif->rx.sring)
		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
					vif->rx.sring);
}