Function iflib_if_transmit

freebsd/net/iflib.c:4072–4150

}

static int
iflib_if_transmit(if_t ifp, struct mbuf *m)
{
	if_ctx_t	ctx = if_getsoftc(ifp);

	iflib_txq_t txq;
	int err, qidx;
	int abdicate = ctx->ifc_sysctl_tx_abdicate;

	if (__predict_false((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0 || !LINK_ACTIVE(ctx))) {
		DBG_COUNTER_INC(tx_frees);
		m_freem(m);
		return (ENETDOWN);
	}

	MPASS(m->m_nextpkt == NULL);
	/* ALTQ-enabled interfaces always use queue 0. */
	qidx = 0;
	if ((NTXQSETS(ctx) > 1) && M_HASHTYPE_GET(m) && !ALTQ_IS_ENABLED(&ifp->if_snd))
		qidx = QIDX(ctx, m);
	/*
	 * XXX calculate buf_ring based on flowid (divvy up bits?)
	 */
	txq = &ctx->ifc_txqs[qidx];

#ifdef DRIVER_BACKPRESSURE
	if (txq->ift_closed) {
		while (m != NULL) {
			next = m->m_nextpkt;
			m->m_nextpkt = NULL;
			m_freem(m);
			DBG_COUNTER_INC(tx_frees);
			m = next;
		}
		return (ENOBUFS);
	}
#endif
#ifdef notyet
	qidx = count = 0;
	mp = marr;
	next = m;
	do {
		count++;
		next = next->m_nextpkt;
	} while (next != NULL);

	if (count > nitems(marr))
		if ((mp = malloc(count*sizeof(struct mbuf *), M_IFLIB, M_NOWAIT)) == NULL) {
			/* XXX check nextpkt */
			m_freem(m);
			/* XXX simplify for now */
			DBG_COUNTER_INC(tx_frees);
			return (ENOBUFS);
		}
	for (next = m, i = 0; next != NULL; i++) {
		mp[i] = next;
		next = next->m_nextpkt;
		mp[i]->m_nextpkt = NULL;