net/virtio: fix Tx packet length stats

In the function virtqueue_enqueue_xmit(), when can_push is true,
vtnet_hdr_size is added to pkt_len by calling rte_pktmbuf_prepend.
which is wrong for pkt stats, virtio header length should be subtracted
before calling stats function.

Fixes: 58169a9c8153 ("net/virtio: support Tx checksum offload")
Cc: stable@dpdk.org
Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Yuanhan Liu <yliu@fridaylinux.org>

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 8560c9c..a483594 100644 (file)
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -299,6 +299,10 @@ virtqueue_enqueue_xmit(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
                /* prepend cannot fail, checked by caller */
                hdr = (struct virtio_net_hdr *)
                        rte_pktmbuf_prepend(cookie, head_size);
+               /* rte_pktmbuf_prepend() counts the hdr size to the pkt length,
+                * which is wrong. Below subtract restores correct pkt size.
+                */
+               cookie->pkt_len -= head_size;
                /* if offload disabled, it is not zeroed below, do it now */
                if (offload == 0) {
                        ASSIGN_UNLESS_EQUAL(hdr->csum_start, 0);