From: Vlad Yasevich <vyasevic@redhat.com>
To: John Hughes <john@atlantech.com>, Vlad Yasevich <vyasevich@gmail.com>
Cc: netdev@vger.kernel.org
Subject: Re: When a TCP segment is split up (to be sent through a TUN device with a small MTU) who should recalculate the checksum?
Date: Fri, 15 Nov 2013 09:41:46 -0500 [thread overview]
Message-ID: <528632AA.2090400@redhat.com> (raw)
In-Reply-To: <5286305F.5060903@atlantech.com>
On 11/15/2013 09:31 AM, John Hughes wrote:
> On 15/11/13 15:20, Vlad Yasevich wrote:
>>
>> Can you check to see if you have the following patch in your kernel
>> commit: 1cdbcb7957cf9e5f841dbcde9b38fd18a804208b
>> Author: Simon Horman <horms@verge.net.au>
>> Date: Sun May 19 15:46:49 2013 +0000
>>
>> net: Loosen constraints for recalculating checksum in skb_segment()
>>
>>
>> This commit help if the forwarding system has to re-segment the data
>> before transition. Especially if the receiving interface had GRO
>> enabled with checksum offloading and the transmitting interface does
>> not support checksum offloading.
>
> No, the Debian 3.10 kernel doesn't seem to have that commit:
>
> Around line 2859 in skbuff.c I see:
>
> if (fskb != skb_shinfo(skb)->frag_list)
> continue;
>
Give it a try. It has helped me in similar situations. If it helps,
we can get it into the stable tree.
-vlad
next prev parent reply other threads:[~2013-11-15 14:41 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-15 8:52 When a TCP segment is split up (to be sent through a TUN device with a small MTU) who should recalculate the checksum? John Hughes
2013-11-15 13:06 ` Eric Dumazet
2013-11-15 14:02 ` John Hughes
2013-11-15 14:20 ` Vlad Yasevich
2013-11-15 14:31 ` John Hughes
2013-11-15 14:41 ` Vlad Yasevich [this message]
2013-11-15 14:55 ` John Hughes
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