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

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Message-ID: <CAOrHB_D2TpjLaE=EyMuL2_vYV05SiQ1rgQJRZ2xA7rqG1qmDWQ@mail.gmail.com>
Date:   Thu, 20 Oct 2016 11:48:18 -0700
From:   Pravin Shelar <pshelar@....org>
To:     Jiri Benc <jbenc@...hat.com>
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 Wed, Oct 19, 2016 at 9:52 AM, Jiri Benc <jbenc@...hat.com> wrote:
> 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.
>
I see, vport send is restoring the skb protocol field. It should be fine then.

> 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