netdev - Re: [PATCH net-next v10 3/5] openvswitch: add support to push and pop mpls for layer3 packets

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Message-ID: <CAOrHB_D0XoGUjSXztNMdektGgTMPxeVfbNF0WcTZuTbR4VYz5g@mail.gmail.com>
Date:	Thu, 2 Jun 2016 15:02:00 -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: [PATCH net-next v10 3/5] openvswitch: add support to push and pop
 mpls for layer3 packets

On Wed, Jun 1, 2016 at 11:24 PM, Simon Horman
<simon.horman@...ronome.com> wrote:
> Allow push and pop mpls actions to act on layer 3 packets by teaching
> them not to access non-existent L2 headers of such packets.
>
> Signed-off-by: Simon Horman <simon.horman@...ronome.com>
> ---
> v10
> * Limit scope of hdr in {push,pop}_mpls()
>
> v9
> * New Patch
> ---
>  net/openvswitch/actions.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
> index 9a3eb7a0ebf4..15f130e4c22b 100644
> --- a/net/openvswitch/actions.c
> +++ b/net/openvswitch/actions.c
> @@ -172,7 +172,8 @@ static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
>
>         skb_postpush_rcsum(skb, new_mpls_lse, MPLS_HLEN);
>
> -       update_ethertype(skb, eth_hdr(skb), mpls->mpls_ethertype);
> +       if (skb->mac_len)
> +               update_ethertype(skb, eth_hdr(skb), mpls->mpls_ethertype);
We can move all ethernet related code in this if block. for example memmove().

>         if (!skb->inner_protocol)
>                 skb_set_inner_protocol(skb, skb->protocol);
>         skb->protocol = mpls->mpls_ethertype;
> @@ -184,7 +185,6 @@ static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
>  static int pop_mpls(struct sk_buff *skb, struct sw_flow_key *key,
>                     const __be16 ethertype)
>  {
> -       struct ethhdr *hdr;
>         int err;
>
>         err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
> @@ -199,11 +199,16 @@ static int pop_mpls(struct sk_buff *skb, struct sw_flow_key *key,
>         __skb_pull(skb, MPLS_HLEN);
>         skb_reset_mac_header(skb);
>
> -       /* skb_mpls_header() is used to locate the ethertype
> -        * field correctly in the presence of VLAN tags.
> -        */
> -       hdr = (struct ethhdr *)(skb_mpls_header(skb) - ETH_HLEN);
> -       update_ethertype(skb, hdr, ethertype);
> +       if (skb->mac_len) {
> +               struct ethhdr *hdr;
> +
> +               /* skb_mpls_header() is used to locate the ethertype
> +                * field correctly in the presence of VLAN tags.
> +                */
> +               hdr = (struct ethhdr *)(skb_mpls_header(skb) - ETH_HLEN);
> +               update_ethertype(skb, hdr, ethertype);
> +       }
same here.