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net: qualcomm: rmnet: rearrange some NOTs

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With the ones' complement arithmetic, the sum of two negated values
is equal to the negation of the sum of the two original values [1].
Rearrange the calculation ip6_payload_sum using this property.

[1] https://tools.ietf.org/html/rfc1071

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alex Elder
2021-06-12 09:37:30 -05:00
committed by David S. Miller
parent 0e6af897fc
commit bbd45f10ed
1 changed files with 2 additions and 2 deletions
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4
drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
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@@ -140,8 +140,8 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
* checksum computed over the pseudo header.
*/
ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4);
ip6_payload_csum = csum16_sub((__force __sum16)~csum_trailer->csum_value,
~ip_header_csum);
ip6_payload_csum = ~csum16_sub((__force __sum16)csum_trailer->csum_value,
ip_header_csum);
length = (ip6h->nexthdr == IPPROTO_UDP) ?
ntohs(((struct udphdr *)txporthdr)->len) :