mac_hwring_tx
return (mac_hwring_tx(mrh, mp));
extern mblk_t *mac_hwring_tx(mac_ring_handle_t, mblk_t *);
extern mblk_t *mac_hwring_tx(mac_ring_handle_t, mblk_t *);
ret_mp = mac_hwring_tx(tx_ringp->hw_rh, mp);