examples/vhost: fix hard forward of jumbo frames

Search the right segment to increase its data length, rather than
wrongly early return and exit the tx function, which leads to drop all jumbo frame packets
when vm2vm is in hard forward mode.

Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>

diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index d2c1852f839dbf86deb1a453a7477c18927fe41b..93319102d7a29489822686baeadfa8b98af5d728 100644 (file)
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -1119,9 +1119,8 @@ virtio_tx_route(struct vhost_dev *vdev, struct rte_mbuf *m, uint16_t vlan_tag)
                return;
        }
 
-       if (vm2vm_mode == VM2VM_HARDWARE) {
-               if (find_local_dest(dev, m, &offset, &vlan_tag) != 0 ||
-                       offset > rte_pktmbuf_tailroom(m)) {
+       if (unlikely(vm2vm_mode == VM2VM_HARDWARE)) {
+               if (unlikely(find_local_dest(dev, m, &offset, &vlan_tag) != 0)) {
                        rte_pktmbuf_free(m);
                        return;
                }
@@ -1135,8 +1134,24 @@ virtio_tx_route(struct vhost_dev *vdev, struct rte_mbuf *m, uint16_t vlan_tag)
 
        m->ol_flags = PKT_TX_VLAN_PKT;
 
-       m->data_len += offset;
-       m->pkt_len += offset;
+       /*
+        * 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;
+
+                       seg->data_len += offset;
+               }
+               m->pkt_len += offset;
+       }
 
        m->vlan_tci = vlan_tag;