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>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 72c6b55af741..651792141f07 100644
--- 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)