rtnetlink: Remove passing of attributes into rtnl_doit functions

With decnet converted, we can finally get rid of rta_buf and its
computations around it. It also gets rid of the minimal header
length verification since all message handlers do that explicitly
anyway.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/addrlabel.c b/net/ipv6/addrlabel.c
index 6f226c8..f083a58 100644
--- a/net/ipv6/addrlabel.c
+++ b/net/ipv6/addrlabel.c
@@ -414,8 +414,7 @@
 	[IFAL_LABEL]		= { .len = sizeof(u32), },
 };
 
-static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
-			     void *arg)
+static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(skb->sk);
 	struct ifaddrlblmsg *ifal;
@@ -530,8 +529,7 @@
 		+ nla_total_size(4);	/* IFAL_LABEL */
 }
 
-static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr* nlh,
-			  void *arg)
+static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr* nlh)
 {
 	struct net *net = sock_net(in_skb->sk);
 	struct ifaddrlblmsg *ifal;