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net: qualcomm: rmnet: simplify some byte order logic
authorAlex Elder <elder@linaro.org>
Mon, 15 Mar 2021 21:51:47 +0000 (16:51 -0500)
committerDavid S. Miller <davem@davemloft.net>
Tue, 16 Mar 2021 03:41:58 +0000 (20:41 -0700)
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>
drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c

index 21d3816..0bfe696 100644 (file)
@@ -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;