On Thu, 2018-04-19 at 08:49 -0700, Eric Dumazet wrote: > While trying to support CHECKSUM_COMPLETE for IPV6 fragments, > I had to experiments various hacks in get_fixed_ipv6_csum(). > I must admit I could not find how to implement this :/ > > However, get_fixed_ipv6_csum() does a lot of redundant operations, > calling csum_partial() twice. > > First csum_partial() computes the checksum of saddr and daddr, > put in @csum_pseudo_hdr. Undone later in the second csum_partial() > computed on whole ipv6 header. > > Then nexthdr is added once, added a second time, then substracted. > > payload_len is added once, then substracted. > > Really all this can be reduced to two add_csum(), to add back 6 bytes > that were removed by mlx4 when providing hw_checksum in RX > descriptor. > > Signed-off-by: Eric Dumazet <eduma...@google.com> > Cc: Saeed Mahameed <sae...@mellanox.com> > Cc: Tariq Toukan <tar...@mellanox.com> > --- > Note: This patch, like other mlx4 patches can definitely wait > Tariq approval, thanks ! >
LGTM, Reviewed-by: Saeed Mahameed <sae...@mellanox.com> > drivers/net/ethernet/mellanox/mlx4/en_rx.c | 21 ++++++++---------- > --- > 1 file changed, 8 insertions(+), 13 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c > b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > index > 5c613c6663da51a4ae792eeb4d8956b54655786b..38c56fb6e5f5970f245dd56c38e > 1fc63a9349a07 100644 > --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c > +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > @@ -593,30 +593,25 @@ static int get_fixed_ipv4_csum(__wsum > hw_checksum, struct sk_buff *skb, > } > > #if IS_ENABLED(CONFIG_IPV6) > -/* In IPv6 packets, besides subtracting the pseudo header checksum, > - * we also compute/add the IP header checksum which > - * is not added by the HW. > +/* In IPv6 packets, hw_checksum lacks 6 bytes from IPv6 header: > + * 4 first bytes : priority, version, flow_lbl > + * and 2 additional bytes : nexthdr, hop_limit. > */ > static int get_fixed_ipv6_csum(__wsum hw_checksum, struct sk_buff > *skb, > struct ipv6hdr *ipv6h) > { > __u8 nexthdr = ipv6h->nexthdr; > - __wsum csum_pseudo_hdr = 0; > + __wsum temp; > > if (unlikely(nexthdr == IPPROTO_FRAGMENT || > nexthdr == IPPROTO_HOPOPTS || > nexthdr == IPPROTO_SCTP)) > return -1; > - hw_checksum = csum_add(hw_checksum, (__force > __wsum)htons(nexthdr)); > > - csum_pseudo_hdr = csum_partial(&ipv6h->saddr, > - sizeof(ipv6h->saddr) + > sizeof(ipv6h->daddr), 0); > - csum_pseudo_hdr = csum_add(csum_pseudo_hdr, (__force > __wsum)ipv6h->payload_len); > - csum_pseudo_hdr = csum_add(csum_pseudo_hdr, > - (__force __wsum)htons(nexthdr)); > - > - skb->csum = csum_sub(hw_checksum, csum_pseudo_hdr); > - skb->csum = csum_add(skb->csum, csum_partial(ipv6h, > sizeof(struct ipv6hdr), 0)); > + /* priority, version, flow_lbl */ > + temp = csum_add(hw_checksum, *(__wsum *)ipv6h); > + /* nexthdr and hop_limit */ > + skb->csum = csum_add(temp, (__force __wsum)*(__be16 > *)&ipv6h->nexthdr); > return 0; > } > #endif