[PATCH net v3] veth: Fixing transmit return status for dropped packets

[PATCH net v3] 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.

Fixes: e314dbdc1c0d ("[NET]: Virtual ethernet device driver.")
Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
 Changes from v2:
- as a fix, targeting 'net' tree instead of 'net-next'
---
 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 v3] veth: Fixing transmit return status for dropped packets

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Fri,  1 Sep 2023 12:09:21 +0800 you 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.
> 
> Fixes: e314dbdc1c0d ("[NET]: Virtual ethernet device driver.")
> Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
> 
> [...]

Here is the summary with links:
  - [net,v3] veth: Fixing transmit return status for dropped packets
    https://git.kernel.org/netdev/net/c/151e887d8ff9

You are awesome, thank you!
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