Re: [PATCH net-next 2/3] net: mpls fixes for GSO

Simon Horman
2016-08-11T07:47:41Z

On Wed, Aug 10, 2016 at 11:43:31PM -0700, Roopa Prabhu wrote:
> From: David Ahern <dsa@cumulusnetworks.com>
>
> Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
> Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>

Thanks. This looks like it should be correct to me. However, I would
appreciate it if you could give me a little time to test it against OvS.

I think the changelog could also do with a few more words given the
complexity (at least to me) of getting this right for all consumers.

> ---
> net/mpls/mpls_gso.c | 24 ++++++++++++++++--------
> net/mpls/mpls_iptunnel.c | 7 +++++++
> 2 files changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c
> index 2055e57..8829ee0 100644
> --- a/net/mpls/mpls_gso.c
> +++ b/net/mpls/mpls_gso.c
> @@ -22,26 +22,28 @@
> static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
> netdev_features_t features)
> {
> + int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
> struct sk_buff *segs = ERR_PTR(-EINVAL);
> + u16 mac_offset = skb->mac_header;
> netdev_features_t mpls_features;
> __be16 mpls_protocol;
> + u16 mac_len = skb->mac_len;
>
> /* Setup inner SKB. */
> mpls_protocol = skb->protocol;
> skb->protocol = skb->inner_protocol;
>
> - /* Push back the mac header that skb_mac_gso_segment() has pulled.
> - * It will be re-pulled by the call to skb_mac_gso_segment() below
> - */
> - __skb_push(skb, skb->mac_len);
> + __skb_pull(skb, tnl_hlen);
> + skb->mac_len = skb_inner_network_offset(skb);
>
> /* Segment inner packet. */
> mpls_features = skb->dev->mpls_features & features;
> segs = skb_mac_gso_segment(skb, mpls_features);
> -
> -
> - /* Restore outer protocol. */
> - skb->protocol = mpls_protocol;
> + if (IS_ERR_OR_NULL(segs)) {
> + skb_gso_error_unwind(skb, mpls_protocol, tnl_hlen, mac_offset,
> + mac_len);
> + goto out;
> + }
>
> /* Re-pull the mac header that the call to skb_mac_gso_segment()
> * above pulled. It will be re-pushed after returning
> @@ -49,6 +51,12 @@ static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
> */
> __skb_pull(skb, skb->data - skb_mac_header(skb));
>
> + /* Restore outer protocol. */
> + skb->protocol = mpls_protocol;
> + for (skb = segs; skb; skb = skb->next)
> + skb->protocol = mpls_protocol;
> +
> +out:
> return segs;
> }
>
> diff --git a/net/mpls/mpls_iptunnel.c b/net/mpls/mpls_iptunnel.c
> index aed872c..87e035a 100644
> --- a/net/mpls/mpls_iptunnel.c
> +++ b/net/mpls/mpls_iptunnel.c
> @@ -90,8 +90,15 @@ static int mpls_xmit(struct sk_buff *skb)
> if (skb_cow(skb, hh_len + new_header_size))
> goto drop;
>
> + skb_reset_mac_header(skb);
> + skb_reset_inner_headers(skb);
> + skb->encapsulation = 1;
> +
> skb_push(skb, new_header_size);
> +
> skb_reset_network_header(skb);
> + skb_reset_transport_header(skb);
> + skb_set_inner_protocol(skb, skb->protocol);
>
> skb->dev = out_dev;
> skb->protocol = htons(ETH_P_MPLS_UC);
> --
> 1.9.1
>