veth: Avoid NAPI scheduling on failed SKB forwarding

When an skb fails to be forwarded to the peer(e.g., skb data buffer
length exceeds MTU), it will not be added to the peer's receive queue.
Therefore, we should schedule the peer's NAPI poll function only when
skb forwarding is successful to avoid unnecessary overhead.

Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Link: https://lore.kernel.org/r/20230824123131.7673-1-liangchen.linux@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index da44bb1331ffb20f66e01dcac1c055ad4a2c4902..d43e62ebc2fcd5d30f4717454ab5c9d089502d15 100644 (file)
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -373,14 +373,13 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
        if (likely(veth_forward_skb(rcv, skb, rq, use_napi) == NET_RX_SUCCESS)) {
                if (!use_napi)
                        dev_lstats_add(dev, length);
+               else
+                       __veth_xdp_flush(rq);
        } else {
 drop:
                atomic64_inc(&priv->dropped);
        }
 
-       if (use_napi)
-               __veth_xdp_flush(rq);
-
        rcu_read_unlock();
 
        return NETDEV_TX_OK;