On Mon, 16 Nov 2020 17:15:47 +0800 Xin Long wrote:
> This patch is to let it always do CRC checksum in sctp_gso_segment()
> by removing CRC flag from the dev features in gre_gso_segment() for
> SCTP over GRE, just as it does in Commit 527beb8ef9c0 ("udp: support
> sctp over udp in skb_udp_tunnel_segment") for SCTP over UDP.
>
> It could set csum/csum_start in GSO CB properly in sctp_gso_segment()
> after that commit, so it would do checksum with gso_make_checksum()
> in gre_gso_segment(), and Commit 622e32b7d4a6 ("net: gre: recompute
> gre csum for sctp over gre tunnels") can be reverted now.
>
> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Makes sense, but does GRE tunnels don't always have a csum.
Is the current hardware not capable of generating CRC csums over
encapsulated patches at all?
I guess UDP tunnels can be configured without the csums as well
so the situation isn't much different.
> diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
> index e0a2465..a5935d4 100644
> --- a/net/ipv4/gre_offload.c
> +++ b/net/ipv4/gre_offload.c
> @@ -15,12 +15,12 @@ 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);
> - bool need_csum, need_recompute_csum, gso_partial;
> struct sk_buff *segs = ERR_PTR(-EINVAL);
> u16 mac_offset = skb->mac_header;
> __be16 protocol = skb->protocol;
> u16 mac_len = skb->mac_len;
> int gre_offset, outer_hlen;
> + bool need_csum, gso_partial;
Nit, rev xmas tree looks broken now.
> if (!skb->encapsulation)
> goto out;
> @@ -41,10 +41,10 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
> skb->protocol = skb->inner_protocol;
>
> need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
> - need_recompute_csum = skb->csum_not_inet;
> skb->encap_hdr_csum = need_csum;
>
> features &= skb->dev->hw_enc_features;
> + features &= ~NETIF_F_SCTP_CRC;
>
> /* segment inner packet. */
> segs = skb_mac_gso_segment(skb, features);
> @@ -99,15 +99,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
> }
>
> *(pcsum + 1) = 0;
> - if (need_recompute_csum && !skb_is_gso(skb)) {
> - __wsum csum;
> -
> - csum = skb_checksum(skb, gre_offset,
> - skb->len - gre_offset, 0);
> - *pcsum = csum_fold(csum);
> - } else {
> - *pcsum = gso_make_checksum(skb, 0);
> - }
> + *pcsum = gso_make_checksum(skb, 0);
> } while ((skb = skb->next));
> out:
> return segs;
