[dpdk-dev] vmxnet3 driver - vlan offload is on end descriptor

[John Guzik <john@shieldxnetworks.com>]

With the new jumbo frame patch a latent bug has appeared to have been uncovered: the VLAN offload is on the last rx descriptor, when rcd->eop is true, not the first rx descriptor, when rcd->sop is true and rcd->eop could be false.
Most likely the reason this has not been seen before is that for non-jumbo frames rcd->eop has always been true when rcd->sop is true as well.

The following patch should fix the problem:

diff --git a/drivers/net/vmxnet3/vmxnet3_rxtx.c b/drivers/net/vmxnet3/vmxnet3_rxtx.c
index 4ac0456..3d4a5eb 100644
--- a/drivers/net/vmxnet3/vmxnet3_rxtx.c
+++ b/drivers/net/vmxnet3/vmxnet3_rxtx.c
@@ -587,12 +587,6 @@ vmxnet3_post_rx_bufs(vmxnet3_rx_queue_t *rxq, uint8_t ring_id)
static void
vmxnet3_rx_offload(const Vmxnet3_RxCompDesc *rcd, struct rte_mbuf *rxm)
{
-       /* Check for hardware stripped VLAN tag */
-       if (rcd->ts) {
-               rxm->ol_flags |= PKT_RX_VLAN_PKT;
-               rxm->vlan_tci = rte_le_to_cpu_16((uint16_t)rcd->tci);
-       }
-
        /* Check for RSS */
        if (rcd->rssType != VMXNET3_RCD_RSS_TYPE_NONE) {
                rxm->ol_flags |= PKT_RX_RSS_HASH;
@@ -737,7 +731,15 @@ vmxnet3_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
                rxq->last_seg = rxm;

                if (rcd->eop) {
-                       rx_pkts[nb_rx++] = rxq->start_seg;
+                       struct rte_mbuf *start = rxq->start_seg;
+
+                       /* Check for hardware stripped VLAN tag */
+                       if (rcd->ts) {
+                               start->ol_flags |= PKT_RX_VLAN_PKT;
+                               start->vlan_tci = rte_le_to_cpu_16((uint16_t)rcd->tci);
+                       }
+
+                       rx_pkts[nb_rx++] = start;
                        rxq->start_seg = NULL;
                }