[PATCH net-next 7/8] net: qualcomm: rmnet: drop some unary NOTs

From: Alex Elder
Date: Sat Jun 12 2021 - 10:38:14 EST


We compare a payload checksum with a pseudo checksum value for
equality in rmnet_map_ipv4_dl_csum_trailer(). Both of those values
are computed with a unary NOT (~) operation. The result of the
comparison is the same if we omit that NOT for both values.

Remove these operations in rmnet_map_ipv6_dl_csum_trailer() also.

Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
---
.../net/ethernet/qualcomm/rmnet/rmnet_map_data.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 610c8b5a8f46a..ed4737d0043d6 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -87,11 +87,11 @@ rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
* header checksum value; it is already accounted for in the
* checksum value found in the trailer.
*/
- ip_payload_csum = ~csum_trailer->csum_value;
+ ip_payload_csum = csum_trailer->csum_value;

- pseudo_csum = ~csum_tcpudp_magic(ip4h->saddr, ip4h->daddr,
- ntohs(ip4h->tot_len) - ip4h->ihl * 4,
- ip4h->protocol, 0);
+ pseudo_csum = csum_tcpudp_magic(ip4h->saddr, ip4h->daddr,
+ ntohs(ip4h->tot_len) - ip4h->ihl * 4,
+ ip4h->protocol, 0);

/* The cast is required to ensure only the low 16 bits are examined */
if (ip_payload_csum != (__sum16)~pseudo_csum) {
@@ -132,13 +132,13 @@ 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(csum_trailer->csum_value, ip_header_csum);
+ 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);
+ pseudo_csum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
+ length, 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