virtio-net: add packet len average only when needed during XDP

There's no need to add packet len average in the case of XDP_PASS
since it will be done soon after skb is created.

Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index a0ef4b08f0e98feea9acb6a85f13a47c0d7ad261..db5924c085aa48e1b038a10351abc47bdd0018ac 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -656,6 +656,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
                xdp.data_end = xdp.data + (len - vi->hdr_len);
                act = bpf_prog_run_xdp(xdp_prog, &xdp);
 
+               if (act != XDP_PASS)
+                       ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
+
                switch (act) {
                case XDP_PASS:
                        /* recalculate offset to account for any header
@@ -671,14 +674,12 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
                                put_page(page);
                                head_skb = page_to_skb(vi, rq, xdp_page,
                                                       offset, len, PAGE_SIZE);
-                               ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
                                return head_skb;
                        }
                        break;
                case XDP_TX:
                        if (unlikely(!virtnet_xdp_xmit(vi, &xdp)))
                                trace_xdp_exception(vi->dev, xdp_prog, act);
-                       ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
                        if (unlikely(xdp_page != page))
                                goto err_xdp;
                        rcu_read_unlock();
@@ -690,7 +691,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
                case XDP_DROP:
                        if (unlikely(xdp_page != page))
                                __free_pages(xdp_page, 0);
-                       ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
                        goto err_xdp;
                }
        }