netdev - Re: [PATCH] net: core: don't account for udp header size when computing seglen

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Date:	Tue, 08 Apr 2014 22:06:00 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	fw@...len.de
Cc:	netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH] net: core: don't account for udp header size when
 computing seglen

From: Florian Westphal <fw@...len.de>
Date: Tue,  8 Apr 2014 22:51:28 +0200

> In case of tcp, gso_size contains the tcpmss.
> 
> For UFO (udp fragmentation offloading) skbs, gso_size is the fragment
> payload size, i.e. we must not account for udp header size.
> 
> Otherwise, when using virtio drivers, a to-be-forwarded UFO GSO packet
> will be needlessly fragmented in the forward path, because we think its
> individual segments are too large for the outgoing link.
> 
> Fixes: de960aa9ab4d ("net: add and use skb_gso_transport_seglen()")
> Cc: Eric Dumazet <eric.dumazet@...il.com>
> Reported-by: Tobias Brunner <tobias@...ongswan.org>
> Signed-off-by: Florian Westphal <fw@...len.de>

I agree completely with the fix, but not necessarily with the Fixes:
tag.

All that commit did was move the code to a common location, it
always had this bug.

I suppose you could list the subsequent commit, the one that started
using this helper in the IP forwarding code, as what this "Fixes".

Thanks Florian.
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