net: qualcomm: rmnet: simplify some byte order logic

In rmnet_map_ipv4_ul_csum_header() and rmnet_map_ipv6_ul_csum_header()
the offset within a packet at which checksumming should commence is
calculated.  This calculation involves byte swapping and a forced type
conversion that makes it hard to understand.

Simplify this by computing the offset in host byte order, then
converting the result when assigning it into the header field.

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 21d38167f96180718fdcda68ed2433d73271b1bf..0bfe69698b278fb1217d8855ccf4aff359d57b05 100644 (file)
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -197,12 +197,10 @@ rmnet_map_ipv4_ul_csum_header(void *iphdr,
                              struct rmnet_map_ul_csum_header *ul_header,
                              struct sk_buff *skb)
 {
-       struct iphdr *ip4h = (struct iphdr *)iphdr;
-       __be16 *hdr = (__be16 *)ul_header, offset;
+       __be16 *hdr = (__be16 *)ul_header;
+       struct iphdr *ip4h = iphdr;
 
-       offset = htons((__force u16)(skb_transport_header(skb) -
-                                    (unsigned char *)iphdr));
-       ul_header->csum_start_offset = offset;
+       ul_header->csum_start_offset = htons(skb_network_header_len(skb));
        ul_header->csum_insert_offset = skb->csum_offset;
        ul_header->csum_enabled = 1;
        if (ip4h->protocol == IPPROTO_UDP)
@@ -239,12 +237,10 @@ rmnet_map_ipv6_ul_csum_header(void *ip6hdr,
                              struct rmnet_map_ul_csum_header *ul_header,
                              struct sk_buff *skb)
 {
-       struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr;
-       __be16 *hdr = (__be16 *)ul_header, offset;
+       __be16 *hdr = (__be16 *)ul_header;
+       struct ipv6hdr *ip6h = ip6hdr;
 
-       offset = htons((__force u16)(skb_transport_header(skb) -
-                                    (unsigned char *)ip6hdr));
-       ul_header->csum_start_offset = offset;
+       ul_header->csum_start_offset = htons(skb_network_header_len(skb));
        ul_header->csum_insert_offset = skb->csum_offset;
        ul_header->csum_enabled = 1;