net: qualcomm: rmnet: trailer value is a checksum

The csum_value field in the rmnet_map_dl_csum_trailer structure is a
"real" Internet checksum.  It is a 16 bit value, in big endian format,
which represents an inverted ones' complement sum over pairs of bytes.

Make that clear by changing its type to __sum16.

This makes a typecast in rmnet_map_ipv4_dl_csum_trailer() and
another in rmnet_map_ipv6_dl_csum_trailer() unnecessary.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 033b8ad..610c8b5 100644 (file)
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -87,7 +87,7 @@ 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 = (__force __sum16)~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,
@@ -132,8 +132,7 @@ 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(csum_trailer->csum_value, ip_header_csum);
 
        length = (ip6h->nexthdr == IPPROTO_UDP) ?
                 ntohs(((struct udphdr *)txporthdr)->len) :

diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h
index be17610..10e7521 100644 (file)
--- a/include/linux/if_rmnet.h
+++ b/include/linux/if_rmnet.h
@@ -25,7 +25,7 @@ struct rmnet_map_dl_csum_trailer {
        u8 flags;                       /* MAP_CSUM_DL_VALID_FLAG */
        __be16 csum_start_offset;
        __be16 csum_length;
-       __be16 csum_value;
+       __sum16 csum_value;
 } __aligned(1);
 
 /* rmnet_map_dl_csum_trailer flags field: