netlink: Remove netlink_compare_arg.trailer

Instead of computing the offset from trailer, this patch computes
netlink_compare_arg_len from the offset of portid and then adds 4
to it.  This allows trailer to be removed.

Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 72c6b55af7410f56450ea995e102c15d2c1c48d1..651792141f076d9ff2100f9adc3bea2d054ff0e0 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -974,10 +974,11 @@ struct netlink_compare_arg
 {
        possible_net_t pnet;
        u32 portid;
-       char trailer[];
 };
 
-#define netlink_compare_arg_len offsetof(struct netlink_compare_arg, trailer)
+/* Doing sizeof directly may yield 4 extra bytes on 64-bit. */
+#define netlink_compare_arg_len \
+       (offsetof(struct netlink_compare_arg, portid) + sizeof(u32))
 
 static inline int netlink_compare(struct rhashtable_compare_arg *arg,
                                  const void *ptr)