if_transmit
int (*if_transmit) /* initiate output routine */
int if_transmit(if_t ifp, struct mbuf *m);
return ((*ifp->if_transmit)(ifp, m));
ifp->if_transmit = start_fn;
return (ifp->if_transmit);
if (ifp->if_transmit == NULL) {
ifp->if_transmit = if_transmit_default;
return ifp->if_transmit(ifp, m);
ifp->if_transmit = ieee80211_vap_transmit;
return (ifp->if_transmit(ifp, m));