On Fri, Feb 5, 2016 at 3:28 PM, Alexander Duyck <adu...@mirantis.com> wrote:
> This patch updates the gre checksum path to follow something much closer to
> the UDP checksum path. By doing this we can avoid needing to do as much
> header inspection and can just make use of the fields we were already
> reading in the sk_buff structure.
>
> Signed-off-by: Alexander Duyck <adu...@mirantis.com>
> ---
> net/ipv4/gre_offload.c | 64
> +++++++++++++++++++++++-------------------------
> 1 file changed, 30 insertions(+), 34 deletions(-)
>
> diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
> index 35a8dd35ed4e..c15441b5ff61 100644
> --- a/net/ipv4/gre_offload.c
> +++ b/net/ipv4/gre_offload.c
> @@ -18,14 +18,14 @@
> static struct sk_buff *gre_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);
> - int ghl;
> struct gre_base_hdr *greh;
> u16 mac_offset = skb->mac_header;
> - int mac_len = skb->mac_len;
> __be16 protocol = skb->protocol;
> - int tnl_hlen;
> - bool csum;
> + u16 mac_len = skb->mac_len;
> + int gre_offset, outer_hlen;
> + bool need_csum;
>
> if (unlikely(skb_shinfo(skb)->gso_type &
> ~(SKB_GSO_TCPV4 |
> @@ -42,64 +42,60 @@ static struct sk_buff *gre_gso_segment(struct sk_buff
> *skb,
> if (!skb->encapsulation)
> goto out;
>
> - if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
> + if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
> goto out;
>
> - greh = (struct gre_base_hdr *)skb_transport_header(skb);
> -
> - ghl = skb_inner_mac_header(skb) - skb_transport_header(skb);
> - if (unlikely(ghl < sizeof(*greh)))
> + if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
> goto out;
>
> - csum = !!(greh->flags & GRE_CSUM);
> - if (csum)
> - skb->encap_hdr_csum = 1;
> + greh = (struct gre_base_hdr *)skb_transport_header(skb);
>
> /* setup inner skb. */
> skb->protocol = greh->protocol;
> skb->encapsulation = 0;
> -
> - if (unlikely(!pskb_may_pull(skb, ghl)))
> - goto out;
> -
> - __skb_pull(skb, ghl);
> + __skb_pull(skb, tnl_hlen);
> skb_reset_mac_header(skb);
> skb_set_network_header(skb, skb_inner_network_offset(skb));
> skb->mac_len = skb_inner_network_offset(skb);
>
> + need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
Should we do a WARN_ON(need_csum && !(greh->flags & GRE_CSUM)) just to
be conservative?
> + skb->encap_hdr_csum = need_csum;
> +
> features &= skb->dev->hw_enc_features;
>
> /* segment inner packet. */
> segs = skb_mac_gso_segment(skb, features);
> if (IS_ERR_OR_NULL(segs)) {
> - skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
> + skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
> + mac_len);
> goto out;
> }
>
> + outer_hlen = skb_tnl_header_len(skb);
> + gre_offset = outer_hlen - tnl_hlen;
> skb = segs;
> - tnl_hlen = skb_tnl_header_len(skb);
> do {
> - __skb_push(skb, ghl);
> - if (csum) {
> - __be32 *pcsum;
> -
> - skb_reset_transport_header(skb);
> -
> - greh = (struct gre_base_hdr *)
> - skb_transport_header(skb);
> - pcsum = (__be32 *)(greh + 1);
> - *pcsum = 0;
> - *(__sum16 *)pcsum = gso_make_checksum(skb, 0);
> - }
> - __skb_push(skb, tnl_hlen - ghl);
> + __be32 *pcsum;
>
> skb_reset_inner_headers(skb);
> skb->encapsulation = 1;
>
> - skb_reset_mac_header(skb);
> - skb_set_network_header(skb, mac_len);
> skb->mac_len = mac_len;
> skb->protocol = protocol;
> +
> + __skb_push(skb, outer_hlen);
> + skb_reset_mac_header(skb);
> + skb_set_network_header(skb, mac_len);
> + skb_set_transport_header(skb, gre_offset);
> +
> + if (!need_csum)
> + continue;
> +
> + greh = (struct gre_base_hdr *)skb_transport_header(skb);
> + pcsum = (__be32 *)(greh + 1);
> +
> + *pcsum = 0;
> + *(__sum16 *)pcsum = gso_make_checksum(skb, 0);
> } while ((skb = skb->next));
> out:
> return segs;
>
