[PATCH net-next] veth: Fixing transmit return status for dropped packets

[PATCH net-next] veth: Fixing transmit return status for dropped packets

[Liang Chen]

The veth_xmit function returns NETDEV_TX_OK even when packets are dropped.
This behavior leads to incorrect calculations of statistics counts, as
well as things like txq->trans_start updates.

Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
---
 drivers/net/veth.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index d43e62ebc2fc..9c6f4f83f22b 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -344,6 +344,7 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
 	struct veth_rq *rq = NULL;
+	int ret = NETDEV_TX_OK;
 	struct net_device *rcv;
 	int length = skb->len;
 	bool use_napi = false;
@@ -378,11 +379,12 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
 	} else {
 drop:
 		atomic64_inc(&priv->dropped);
+		ret = NET_XMIT_DROP;
 	}
 
 	rcu_read_unlock();
 
-	return NETDEV_TX_OK;
+	return ret;
 }
 
 static u64 veth_stats_tx(struct net_device *dev, u64 *packets, u64 *bytes)
-- 
2.39.3

Re: [PATCH net-next] veth: Fixing transmit return status for dropped packets

[Eric Dumazet]

On Thu, Aug 31, 2023 at 11:06 AM Liang Chen <liangchen.linux@gmail.com> wrote:
>
> The veth_xmit function returns NETDEV_TX_OK even when packets are dropped.
> This behavior leads to incorrect calculations of statistics counts, as
> well as things like txq->trans_start updates.
>
> Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> ---

We kindly ask for net patches to include a Fixes: tag.

If we receive hundreds of patches without them, it takes hours of work
for reviewers
to do the _needed_ work.

We need your help.

Fixes: e314dbdc1c0d ("[NET]: Virtual ethernet device driver.")

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks.