On Fri, Feb 5, 2016 at 3:27 PM, Alexander Duyck <adu...@mirantis.com> wrote:
> This patch moves the checksum maintained by GSO out of skb->csum and into
> the GSO context block in order to allow for us to work on outer checksums
> while maintaining the inner checksum offsets in the case of the inner
> checksum being offloaded, while the outer checksums will be computed.
>
> While updating the code I also did a minor cleanu-up on gso_make_checksum.
> The change is mostly to make it so that we store the values and compute the
> checksum instead of computing the checksum and then storing the values we
> needed to update.
>
Typo in commit log (cleanu-up)
Acked-by: Tom Herbert <t...@herbertland.com>
> Signed-off-by: Alexander Duyck <adu...@mirantis.com>
> ---
> include/linux/skbuff.h | 14 +++++++-------
> net/core/skbuff.c | 16 +++++++++-------
> 2 files changed, 16 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 61b8cef73296..33c3807b618a 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -3549,6 +3549,7 @@ static inline struct sec_path *skb_sec_path(struct
> sk_buff *skb)
> struct skb_gso_cb {
> int mac_offset;
> int encap_level;
> + __wsum csum;
> __u16 csum_start;
> };
> #define SKB_SGO_CB_OFFSET 32
> @@ -3585,15 +3586,14 @@ static inline int gso_pskb_expand_head(struct sk_buff
> *skb, int extra)
> */
> static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
> {
> - int plen = SKB_GSO_CB(skb)->csum_start - skb_headroom(skb) -
> - skb_transport_offset(skb);
> - __wsum partial;
> + unsigned char *csum_start = skb_transport_header(skb);
> + int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
> + __wsum partial = SKB_GSO_CB(skb)->csum;
>
> - partial = csum_partial(skb_transport_header(skb), plen, skb->csum);
> - skb->csum = res;
> - SKB_GSO_CB(skb)->csum_start -= plen;
> + SKB_GSO_CB(skb)->csum = res;
> + SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
>
> - return csum_fold(partial);
> + return csum_fold(csum_partial(csum_start, plen, partial));
> }
>
> static inline bool skb_is_gso(const struct sk_buff *skb)
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index b2df375ec9c2..02c638a643ea 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -3100,11 +3100,12 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
>
> if (!sg && !nskb->remcsum_offload) {
> nskb->ip_summed = CHECKSUM_NONE;
> - nskb->csum = skb_copy_and_csum_bits(head_skb, offset,
> - skb_put(nskb,
> len),
> - len, 0);
> + SKB_GSO_CB(nskb)->csum =
> + skb_copy_and_csum_bits(head_skb, offset,
> + skb_put(nskb, len),
> + len, 0);
> SKB_GSO_CB(nskb)->csum_start =
> - skb_headroom(nskb) + doffset;
> + skb_headroom(nskb) + doffset;
> continue;
> }
>
> @@ -3171,11 +3172,12 @@ skip_fraglist:
>
> perform_csum_check:
> if (!csum && !nskb->remcsum_offload) {
> - nskb->csum = skb_checksum(nskb, doffset,
> - nskb->len - doffset, 0);
> nskb->ip_summed = CHECKSUM_NONE;
> + SKB_GSO_CB(nskb)->csum =
> + skb_checksum(nskb, doffset,
> + nskb->len - doffset, 0);
> SKB_GSO_CB(nskb)->csum_start =
> - skb_headroom(nskb) + doffset;
> + skb_headroom(nskb) + doffset;
> }
> } while ((offset += len) < head_skb->len);
>
>
