netlink: Improve returned error codes

Make nlmsg_trim(), nlmsg_cancel(), genlmsg_cancel(), and
nla_nest_cancel() void functions.

Return -EMSGSIZE instead of -1 if the provided message buffer is not
big enough.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_red.c

@@ -281,7 +281,8 @@ static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
 	return nla_nest_end(skb, opts);
 
 nla_put_failure:
-	return nla_nest_cancel(skb, opts);
+	nla_nest_cancel(skb, opts);
+	return -EMSGSIZE;
 }
 
 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)