examples/vhost: avoid inserting vlan twice

Check if it has already been vlan-tagged packet, if true, avoid inserting a
duplicated vlan tag into it.

This is a possible case when guest has the capability of inserting vlan tag.

Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
Acked-by: Huawei Xie <huawei.xie@intel.com>

diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index 3a35359..5c72a59 100644 (file)
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -1115,6 +1115,7 @@ virtio_tx_route(struct vhost_dev *vdev, struct rte_mbuf *m, uint16_t vlan_tag)
        unsigned len, ret, offset = 0;
        const uint16_t lcore_id = rte_lcore_id();
        struct virtio_net *dev = vdev->dev;
+       struct ether_hdr *nh;
 
        /*check if destination is local VM*/
        if ((vm2vm_mode == VM2VM_SOFTWARE) && (virtio_tx_local(vdev, m) == 0)) {
@@ -1135,28 +1136,38 @@ virtio_tx_route(struct vhost_dev *vdev, struct rte_mbuf *m, uint16_t vlan_tag)
        tx_q = &lcore_tx_queue[lcore_id];
        len = tx_q->len;
 
-       m->ol_flags = PKT_TX_VLAN_PKT;
+       nh = rte_pktmbuf_mtod(m, struct ether_hdr *);
+       if (unlikely(nh->ether_type == rte_cpu_to_be_16(ETHER_TYPE_VLAN))) {
+               /* Guest has inserted the vlan tag. */
+               struct vlan_hdr *vh = (struct 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 = PKT_TX_VLAN_PKT;
 
-       /*
-        * 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;
-               else {
-                       struct rte_mbuf *seg = m;
+               /*
+                * 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;
+                       else {
+                               struct rte_mbuf *seg = m;
 
-                       while ((seg->next != NULL) &&
-                               (offset > rte_pktmbuf_tailroom(seg)))
-                               seg = seg->next;
+                               while ((seg->next != NULL) &&
+                                       (offset > rte_pktmbuf_tailroom(seg)))
+                                       seg = seg->next;
 
-                       seg->data_len += offset;
+                               seg->data_len += offset;
+                       }
+                       m->pkt_len += offset;
                }
-               m->pkt_len += offset;
-       }
 
-       m->vlan_tci = vlan_tag;
+               m->vlan_tci = vlan_tag;
+       }
 
        tx_q->m_table[len] = m;
        len++;