On Fri, Feb 5, 2016 at 3:27 PM, Alexander Duyck <adu...@mirantis.com> wrote:
> This patch addresses two main issues.
>
> First in the case of remote checksum offload we were avoiding dealing with
> scatter-gather issues. As a result it would be possible to assemble a
> series of frames that used frags instead of being linearized as they should
> have if remote checksum offload was enabled.
>
> Second I have updated the code so that we now let GSO take care of doing
> the checksum on the data itself and drop the special case that was added
> for remote checksum offload.
>
Did you test this (with vxlan or GUE)?
> Signed-off-by: Alexander Duyck <adu...@mirantis.com>
> ---
> net/core/skbuff.c | 10 ++++++----
> net/ipv4/udp_offload.c | 22 ++++++++++------------
> 2 files changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 02c638a643ea..9c065ac72e87 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -3098,8 +3098,9 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
> if (nskb->len == len + doffset)
> goto perform_csum_check;
>
> - if (!sg && !nskb->remcsum_offload) {
> - nskb->ip_summed = CHECKSUM_NONE;
> + if (!sg) {
> + if (!nskb->remcsum_offload)
> + nskb->ip_summed = CHECKSUM_NONE;
> SKB_GSO_CB(nskb)->csum =
> skb_copy_and_csum_bits(head_skb, offset,
> skb_put(nskb, len),
> @@ -3171,8 +3172,9 @@ skip_fraglist:
> nskb->truesize += nskb->data_len;
>
> perform_csum_check:
> - if (!csum && !nskb->remcsum_offload) {
> - nskb->ip_summed = CHECKSUM_NONE;
> + if (!csum) {
> + if (!nskb->remcsum_offload)
> + nskb->ip_summed = CHECKSUM_NONE;
> SKB_GSO_CB(nskb)->csum =
> skb_checksum(nskb, doffset,
> nskb->len - doffset, 0);
> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
> index ce64c2b7ba55..86687f58d613 100644
> --- a/net/ipv4/udp_offload.c
> +++ b/net/ipv4/udp_offload.c
> @@ -66,6 +66,16 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct
> sk_buff *skb,
>
> features &= skb->dev->hw_enc_features;
>
> + /* The only checksum offload we care about from here on out is the
> + * outer one so strip the existing checksum feature flags and
> + * instead set the flag based on our outer checksum offload value.
> + */
> + if (remcsum) {
> + features &= ~NETIF_F_CSUM_MASK;
> + if (offload_csum)
> + features |= NETIF_F_HW_CSUM;
> + }
> +
> /* segment inner packet. */
> segs = gso_inner_segment(skb, features);
> if (IS_ERR_OR_NULL(segs)) {
> @@ -116,18 +126,6 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct
> sk_buff *skb,
> skb->ip_summed = CHECKSUM_PARTIAL;
> skb->csum_start = skb_transport_header(skb) -
> skb->head;
> skb->csum_offset = offsetof(struct udphdr, check);
> - } else if (remcsum) {
> - /* Need to calculate checksum from scratch,
> - * inner checksums are never when doing
> - * remote_checksum_offload.
> - */
> -
> - skb->csum = skb_checksum(skb, udp_offset,
> - skb->len - udp_offset,
> - 0);
> - uh->check = csum_fold(skb->csum);
> - if (uh->check == 0)
> - uh->check = CSUM_MANGLED_0;
> } else {
> uh->check = gso_make_checksum(skb, ~uh->check);
>
>
