From 2d943adf860302a4c7bfee498e64ded9fe7d9dba Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 19 Apr 2018 08:49:29 -0700 Subject: [PATCH] net/mlx4_en: optimizes get_fixed_ipv6_csum() 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 Cc: Saeed Mahameed Cc: Tariq Toukan Reviewed-by: Saeed Mahameed Acked-by: Tariq Toukan Signed-off-by: David S. Miller --- 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 efc55feddc5c..9f54ccbddea7 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