netdev - Re: [PATCH net-next v2 3/5] bpf: BPF for lightweight tunnel encapsulation

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Date:   Tue, 1 Nov 2016 14:03:52 -0700
From:   Thomas Graf <tgraf@...g.ch>
To:     David Ahern <dsa@...ulusnetworks.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Tom Herbert <tom@...bertland.com>,
        roopa <roopa@...ulusnetworks.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v2 3/5] bpf: BPF for lightweight tunnel encapsulation

On 1 November 2016 at 13:11, David Ahern <dsa@...ulusnetworks.com> wrote:
> On 10/31/16 6:37 PM, Thomas Graf wrote:
>>  - Perform simple encapsulation where offload is of no concern.
>>    (The existing funtionality to attach a tunnel key to the skb
>>     and redirect to a tunnel net_device to allow for offload
>>     continues to work obviously).
>
> have you tested the adding of headers with large packets hitting gso and fragmentation? Wondering if mtu is used properly when headers are added and the lwt->headroom is not accounted. See 14972cbd34ff668c390cbd2e6497323484c9e812

Thanks for the pointer David, I will look into this.

The packet size is currently limited to this when adding l2 headers:
skb->dev->mtu + skb->dev->hard_header_len