| Message ID | m1oc54i242.fsf@fess.ebiederm.org |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: ebiederm@xmission.com (Eric W. Biederman) Date: Mon, 21 Mar 2011 14:40:29 -0700 > > Commit 44540960 "veth: move loopback logic to common location" introduced > a bug in the packet counters. I don't understand why that happened as it > is not explained in the comments and the mut check in dev_forward_skb > retains the assumption that skb->len is the total length of the packet. > > I just measured this emperically by setting up a veth pair between two > noop network namespaces setting and attempting a telnet connection between > the two. I saw three packets in each direction and the byte counters were > exactly 14*3 = 42 bytes high in each direction. I got the actual > packet lengths with tcpdump. > > So remove the extra ETH_HLEN from the veth byte count totals. > > Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/veth.c b/drivers/net/veth.c index 105d7f0..2de9b90 100644 --- a/drivers/net/veth.c +++ b/drivers/net/veth.c @@ -171,7 +171,7 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev) if (skb->ip_summed == CHECKSUM_NONE) skb->ip_summed = rcv_priv->ip_summed; - length = skb->len + ETH_HLEN; + length = skb->len; if (dev_forward_skb(rcv, skb) != NET_RX_SUCCESS) goto rx_drop;
Commit 44540960 "veth: move loopback logic to common location" introduced a bug in the packet counters. I don't understand why that happened as it is not explained in the comments and the mut check in dev_forward_skb retains the assumption that skb->len is the total length of the packet. I just measured this emperically by setting up a veth pair between two noop network namespaces setting and attempting a telnet connection between the two. I saw three packets in each direction and the byte counters were exactly 14*3 = 42 bytes high in each direction. I got the actual packet lengths with tcpdump. So remove the extra ETH_HLEN from the veth byte count totals. Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> --- drivers/net/veth.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)