INVALID_GRANT_HANDLE
if (xnbp->xnb_rx_ring_handle != INVALID_GRANT_HANDLE) {
xnbp->xnb_rx_ring_handle = INVALID_GRANT_HANDLE;
if (xnbp->xnb_tx_ring_handle != INVALID_GRANT_HANDLE) {
xnbp->xnb_tx_ring_handle = INVALID_GRANT_HANDLE;
xnbp->xnb_tx_ring_handle = INVALID_GRANT_HANDLE;
xnbp->xnb_rx_ring_handle = INVALID_GRANT_HANDLE;