emx_get_txring_inuse
sc->tx_ring_inuse = emx_get_txring_inuse(sc, polling);
static int emx_get_txring_inuse(const struct emx_softc *, boolean_t);
txr_cnt = emx_get_txring_inuse(sc, TRUE);
sc->tx_ring_inuse = emx_get_txring_inuse(sc, FALSE);