llc: use limited socket backlog

Make llc adapt to the limited socket backlog change.

Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/llc/llc_conn.c

@@ -827,7 +827,8 @@ void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
 	else {
 		dprintk("%s: adding to backlog...\n", __func__);
 		llc_set_backlog_type(skb, LLC_PACKET);
-		sk_add_backlog(sk, skb);
+		if (sk_add_backlog_limited(sk, skb))
+			goto drop_unlock;
 	}
 out:
 	bh_unlock_sock(sk);