netdev - Re: [PATCH net-next v3 3/4] bpf: BPF for lightweight tunnel infrastructure

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Message-ID: <20161130085756.GD16856@pox.localdomain>
Date:   Wed, 30 Nov 2016 09:57:56 +0100
From:   Thomas Graf <tgraf@...g.ch>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, daniel@...earbox.net,
        tom@...bertland.com, roopa@...ulusnetworks.com,
        hannes@...essinduktion.org
Subject: Re: [PATCH net-next v3 3/4] bpf: BPF for lightweight tunnel
 infrastructure

On 11/29/16 at 11:01pm, Alexei Starovoitov wrote:
> On Wed, Nov 30, 2016 at 07:48:51AM +0100, Thomas Graf wrote:
> > Should we check in __bpf_redirect_common() whether mac_header <
> > nework_header then or add it to lwt-bpf conditional on
> > dev_is_mac_header_xmit()?
> 
> may be only extra 'if' in lwt-bpf is all we need?

Agreed, I will add a mac_header < network_header check to lwt-bpf if we
redirect to an l2 device.

> I'm still missing what will happen if we 'forget' to do
> bpf_skb_push() inside the lwt-bpf program, but still do redirect
> in lwt_xmit stage to l2 netdev...

The same as for a AF_PACKET socket not providing an actual L2 header.
I will add a test case to cover this scenario as well.