[IPV6]: Fix tunnel list locking in sit.c

Signed-off-by: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/sit.c

@@ -135,10 +135,10 @@ static void ipip6_tunnel_link(struct ip_tunnel *t)
 {
 	struct ip_tunnel **tp = ipip6_bucket(t);
 
-	write_lock_bh(&ipip6_lock);
 	t->next = *tp;
-	write_unlock_bh(&ipip6_lock);
+	write_lock_bh(&ipip6_lock);
 	*tp = t;
+	write_unlock_bh(&ipip6_lock);
 }
 
 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)