netdev - Re: [PATCH net v2 2/2] net: bcmgenet: fix skb_len in bcmgenet_xmit

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Date:	Thu, 24 Mar 2016 15:15:25 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	pgynther@...gle.com
Cc:	netdev@...r.kernel.org, f.fainelli@...il.com,
	jaedon.shin@...il.com, edumazet@...gle.com
Subject: Re: [PATCH net v2 2/2] net: bcmgenet: fix skb_len in
 bcmgenet_xmit_single()

From: Petri Gynther <pgynther@...gle.com>
Date: Thu, 24 Mar 2016 11:27:21 -0700

> skb_len needs to be skb_headlen(skb) in bcmgenet_xmit_single().
> 
> Fragmented skbs can have only Ethernet + IP + TCP headers (14+20+20=54 bytes)
> in the linear buffer, followed by the rest in fragments. Bumping skb_len to
> ETH_ZLEN would be incorrect for this case, as it would introduce garbage
> between TCP header and the fragment data.
> 
> This also works with regular/non-fragmented small packets < ETH_ZLEN bytes.
> Successfully tested this on GENETv3 with 42-byte ARP frames.
> 
> For testing, I used:
> ethtool -K eth0 tx-checksum-ipv4 off
> ethtool -K eth0 tx-checksum-ipv6 off
> echo 0 > /proc/sys/net/ipv4/tcp_timestamps
> 
> Fixes: 1c1008c793fa ("net: bcmgenet: add main driver file")
> Signed-off-by: Petri Gynther <pgynther@...gle.com>
> Acked-by: Eric Dumazet <edumazet@...gle.com>

Applied.