[IPV6]: Add UDP_MIB_{SND,RCV}BUFERRORS handling.

Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/udp.c

@@ -345,6 +345,8 @@ out:
 
 static inline int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 {
+	int rc;
+
 	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) {
 		kfree_skb(skb);
 		return -1;
@@ -356,7 +358,10 @@ static inline int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 		return 0;
 	}
 
-	if (sock_queue_rcv_skb(sk,skb)<0) {
+	if ((rc = sock_queue_rcv_skb(sk,skb)) < 0) {
+		/* Note that an ENOMEM error is charged twice */
+		if (rc == -ENOMEM)
+			UDP_INC_STATS_BH(UDP_MIB_RCVBUFERRORS);
 		UDP6_INC_STATS_BH(UDP_MIB_INERRORS);
 		kfree_skb(skb);
 		return 0;
@@ -857,6 +862,16 @@ out:
 		UDP6_INC_STATS_USER(UDP_MIB_OUTDATAGRAMS);
 		return len;
 	}
+	/*
+	 * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space.  Reporting
+	 * ENOBUFS might not be good (it's not tunable per se), but otherwise
+	 * we don't have a good statistic (IpOutDiscards but it can be too many
+	 * things).  We could add another new stat but at least for now that
+	 * seems like overkill.
+	 */
+	if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
+		UDP_INC_STATS_USER(UDP_MIB_SNDBUFERRORS);
+	}
 	return err;
 
 do_confirm: