netdev - Re: [PATCH net-next] openvswitch: correctly fragment packet with mpls headers

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Date:   Tue, 4 Oct 2016 09:53:25 -0700
From:   Pravin Shelar <pshelar@....org>
To:     Jiri Benc <jbenc@...hat.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        David Ahern <dsa@...ulusnetworks.com>
Subject: Re: [PATCH net-next] openvswitch: correctly fragment packet with mpls headers

On Tue, Oct 4, 2016 at 2:28 AM, Jiri Benc <jbenc@...hat.com> wrote:
> On Tue, 4 Oct 2016 10:24:58 +0200, Jiri Benc wrote:
>> On Mon, 3 Oct 2016 11:04:46 -0700, Pravin Shelar wrote:
>> > This is not correct way to detect MPLS packet. inner_protocol can be
>> > set by any tunnel device for using tunnel offloads. So this would
>> > break the fragmentation for encapsulated packets.
>>
>> You're right, stupid me.
>
> Actually, too little caffeine in the morning. I actually did consider
> this and I believe my patch is correct. It doesn't matter what the
> encapsulation is, we want to fragment the *inner* packet. And this is
> exactly what this patch does.
>
> Besides, the only case is MPLS anyway. I'm not aware of any code path
> that could lead us to here, set inner protocol and not be MPLS. But
> even if it is, it should work, provided the encapsulation header is
> identical for all fragments and smaller than MAX_L2_LEN.
>

This code can be executed on encapsulated geneve or vxlan packets. So
in that case encapsulation header would not be same for all fragments.