netdev - Re: [ovs-dev] [PATCH net-next v11 3/6] openvswitch: set skb protocol and mac

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Date:	Thu, 7 Jul 2016 13:52:25 -0700
From:	pravin shelar <pshelar@....org>
To:	Simon Horman <simon.horman@...ronome.com>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	ovs dev <dev@...nvswitch.org>
Subject: Re: [ovs-dev] [PATCH net-next v11 3/6] openvswitch: set skb protocol
 and mac_len when receiving on internal device

On Wed, Jul 6, 2016 at 10:59 AM, Simon Horman
<simon.horman@...ronome.com> wrote:
> * Set skb protocol based on contents of packet. I have observed this is
>   necessary to get actual protocol of a packet when it is injected into an
>   internal device e.g. by libnet in which case skb protocol will be set to
>   ETH_ALL.
>
I am not sure what do yo mean by ETH_ALL. I could not find it in the kernel.
anyways, Can we fix libnet to set skb->protocol field correctly? The
change is introducing overhead for every packet received on internal
port.

> * Set the mac_len which has been observed to not be set up correctly when
>   an ARP packet is generated and sent via an openvswitch bridge.
>   My test case is a scenario where there are two open vswtich bridges.
>   One outputs to a tunnel port which egresses on the other.
>
> The motivation for this is that support for outputting to layer 3 (non-tap)
> GRE tunnels as implemented by a subsequent patch depends on protocol and
> mac_len being set correctly on receive.
>
The commit msg and the change does not match anymore.


> Signed-off-by: Simon Horman <simon.horman@...ronome.com>
>
> ---
> v11
> * Do not set mac_len.
>   Instead of relying on mac_len follow-up patches now
>   use skb_unset_mac_header()
>
> v10
> * Set mac_len
>
> v9
> * New patch
> ---
>  net/openvswitch/vport-internal_dev.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
> index 434e04c3a189..32d8e94d9bff 100644
> --- a/net/openvswitch/vport-internal_dev.c
> +++ b/net/openvswitch/vport-internal_dev.c
> @@ -48,6 +48,9 @@ static int internal_dev_xmit(struct sk_buff *skb, struct net_device *netdev)
>  {
>         int len, err;
>
> +       skb->protocol = eth_type_trans(skb, netdev);
> +       skb_push(skb, ETH_HLEN);
> +