Subject: Re: [PATCH net v2] gso: Update tunnel segmentation to support Tx checksum offload

From: Alexander Duyck <[email-masked]>
Date: Thu, 11 Jul 2013 10:58:37 -0700

On 07/11/2013 06:51 AM, Eric Dumazet wrote:
> On Thu, 2013-07-11 at 00:45 -0700, Pravin Shelar wrote:
>
>> Nice speculation ;)
> Indeed ;) Sorry Pravin !
>
>> I did some digging and found following commit causing problem with GRE
>> TSO on bnx setup.
> Thanks for taking care of this problem.
>
>

I may have found another issue, but I don't think it is related to my
patch.  Specifically it seems like there is some MTU calculation
somewhere that is is off by 14 bytes when using gretap.

I'm just setting up an endpoint and using it back to back with the
following commands:
 ip link add tun0 type gretap remote 192.168.11.129 local 192.168.11.1
 ifconfig tun0 192.168.100.1/24

When I try to ping with a size of 1421 or more, it is being dropped and
being counted as a tx error for the tunnel.  It looks like 3.9 doesn't
have this issue.  I'll try to figure out the root cause before the end
of today.

Thanks,

Alex