udp: Add MIB counters for rcvbuferrors

Add MIB counters for rcvbuferrors in UDP to help diagnose problems.
Signed-off-by: James M Leddy <james.leddy@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp.c

@@ -1588,8 +1588,11 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		goto csum_error;
 
 
-	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf))
+	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf)) {
+		UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS,
+				 is_udplite);
 		goto drop;
+	}
 
 	rc = 0;
 

net/ipv6/udp.c

@@ -674,8 +674,11 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 			goto csum_error;
 	}
 
-	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf))
+	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf)) {
+		UDP6_INC_STATS_BH(sock_net(sk),
+				  UDP_MIB_RCVBUFERRORS, is_udplite);
 		goto drop;
+	}
 
 	skb_dst_drop(skb);
 
@@ -690,6 +693,7 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	bh_unlock_sock(sk);
 
 	return rc;
+
 csum_error:
 	UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
 drop: