[PATCH net-next 8/8] net: qualcomm: rmnet: IPv6 payload length is simple

From: Alex Elder
Date: Sat Jun 12 2021 - 10:38:53 EST


We don't support any extension headers for IPv6 packets. Extension
headers therefore contribute 0 bytes to the payload length. As a
result we can just use the IPv6 payload length as the length used to
compute the pseudo header checksum for both UDP and TCP messages.

Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
---
drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index ed4737d0043d6..a6ce22f60a00c 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -114,7 +114,6 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
__sum16 *csum_field, pseudo_csum;
__sum16 ip6_payload_csum;
__be16 ip_header_csum;
- u32 length;

/* Checksum offload is only supported for UDP and TCP protocols;
* the packet cannot include any IPv6 extension headers
@@ -134,11 +133,9 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4);
ip6_payload_csum = csum16_sub(csum_trailer->csum_value, ip_header_csum);

- length = (ip6h->nexthdr == IPPROTO_UDP) ?
- ntohs(((struct udphdr *)txporthdr)->len) :
- ntohs(ip6h->payload_len);
pseudo_csum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
- length, ip6h->nexthdr, 0);
+ ntohs(ip6h->payload_len),
+ ip6h->nexthdr, 0);

/* It's sufficient to compare the IP payload checksum with the
* negated pseudo checksum to determine whether the packet
--
2.27.0