netdev - Re: [PATCH net-next v12 5/9] openvswitch: add processing of L3 packets

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Date:   Wed, 19 Oct 2016 18:52:06 +0200
From:   Jiri Benc <jbenc@...hat.com>
To:     Pravin Shelar <pshelar@....org>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        ovs dev <dev@...nvswitch.org>,
        Lorand Jakab <lojakab@...co.com>,
        Simon Horman <simon.horman@...ronome.com>
Subject: Re: [PATCH net-next v12 5/9] openvswitch: add processing of L3
 packets

On Tue, 18 Oct 2016 22:13:45 -0700, Pravin Shelar wrote:
> On Mon, Oct 17, 2016 at 6:02 AM, Jiri Benc <jbenc@...hat.com> wrote:
> > -       skb_reset_network_header(skb);
> > +               skb->protocol = parse_ethertype(skb);
> 
> I am not sure about changing skb->protocol here.
> By changing this skb loosing information about packet type. Therefore
> if packet re-enters OVS (through different bridge), this packet would
> look like L3 packet. function key_extract_mac_proto() would not see
> TEB type packet.

This should be okay. If the packet is sent out to an Ethernet interface
(whatever interface it is), skb->protocol needs to contain the payload
type. We're not interested in ETH_P_TEB. If the packet is sent out to
an ARPHRD_NONE interface, ETH_P_TEB is pushed back.

Basically, what we're doing here is unconditionally converting
ETH_P_TEB packets *coming from ARPHRD_NONE interfaces* (this is
important) into regular Ethernet packets. Which is exactly what we want.

Am I missing something?

 Jiri