MVNETA_RX_RING_NEXT
CTASSERT(MVNETA_RX_RING_CNT > 1 && MVNETA_RX_RING_NEXT(MVNETA_RX_RING_CNT) ==
cons = MVNETA_RX_RING_NEXT(cons);
prod = MVNETA_RX_RING_NEXT(prod);