Function virtio_tx_route

dpdk/examples/vhost/main.c:1251–1335

* This function routes the TX packet to the correct interface. This * may be a local device or the physical port. */

 * may be a local device or the physical port.
 */
static __rte_always_inline void
virtio_tx_route(struct vhost_dev *vdev, struct rte_mbuf *m, uint16_t vlan_tag)
{
	struct mbuf_table *tx_q;
	unsigned offset = 0;
	const uint16_t lcore_id = rte_lcore_id();
	struct rte_ether_hdr *nh;


	nh = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
	if (unlikely(rte_is_broadcast_ether_addr(&nh->dst_addr))) {
		struct vhost_dev *vdev2;

		TAILQ_FOREACH(vdev2, &vhost_dev_list, global_vdev_entry) {
			if (vdev2 != vdev)
				sync_virtio_xmit(vdev2, vdev, m);
		}
		goto queue2nic;
	}

	/*check if destination is local VM*/
	if ((vm2vm_mode == VM2VM_SOFTWARE) && (virtio_tx_local(vdev, m) == 0))
		return;

	if (unlikely(vm2vm_mode == VM2VM_HARDWARE)) {
		if (unlikely(find_local_dest(vdev, m, &offset,
					     &vlan_tag) != 0)) {
			rte_pktmbuf_free(m);
			return;
		}
	}

	RTE_LOG_DP(DEBUG, VHOST_DATA,
		"(%d) TX: MAC address is external\n", vdev->vid);

queue2nic:

	/*Add packet to the port tx queue*/
	tx_q = &lcore_tx_queue[lcore_id];

	nh = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
	if (unlikely(nh->ether_type == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN))) {
		/* Guest has inserted the vlan tag. */
		struct rte_vlan_hdr *vh = (struct rte_vlan_hdr *) (nh + 1);
		uint16_t vlan_tag_be = rte_cpu_to_be_16(vlan_tag);
		if ((vm2vm_mode == VM2VM_HARDWARE) &&
			(vh->vlan_tci != vlan_tag_be))
			vh->vlan_tci = vlan_tag_be;
	} else {
		m->ol_flags |= RTE_MBUF_F_TX_VLAN;

		/*
		 * Find the right seg to adjust the data len when offset is
		 * bigger than tail room size.
		 */
		if (unlikely(vm2vm_mode == VM2VM_HARDWARE)) {
			if (likely(offset <= rte_pktmbuf_tailroom(m)))
				m->data_len += offset;