[IPV4]: add the UdpSndbufErrors and UdpRcvbufErrors MIBs

Signed-off-by: Martin Bligh <mbligh@google.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>

include/linux/snmp.h

@@ -155,6 +155,8 @@ enum
 	UDP_MIB_NOPORTS,			/* NoPorts */
 	UDP_MIB_INERRORS,			/* InErrors */
 	UDP_MIB_OUTDATAGRAMS,			/* OutDatagrams */
+	UDP_MIB_RCVBUFERRORS,			/* RcvbufErrors */
+	UDP_MIB_SNDBUFERRORS,			/* SndbufErrors */
 	__UDP_MIB_MAX
 };
 

net/ipv4/proc.c

@@ -173,6 +173,8 @@ static const struct snmp_mib snmp4_udp_list[] = {
 	SNMP_MIB_ITEM("NoPorts", UDP_MIB_NOPORTS),
 	SNMP_MIB_ITEM("InErrors", UDP_MIB_INERRORS),
 	SNMP_MIB_ITEM("OutDatagrams", UDP_MIB_OUTDATAGRAMS),
+	SNMP_MIB_ITEM("RcvbufErrors", UDP_MIB_RCVBUFERRORS),
+	SNMP_MIB_ITEM("SndbufErrors", UDP_MIB_SNDBUFERRORS),
 	SNMP_MIB_SENTINEL
 };
 

net/ipv4/udp.c

@@ -662,6 +662,16 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		UDP_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:
@@ -981,6 +991,7 @@ static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)
 static int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 {
 	struct udp_sock *up = udp_sk(sk);
+	int rc;
 
 	/*
 	 *	Charge it to the socket, dropping if the queue is full.
@@ -1027,7 +1038,10 @@ static int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	}
 
-	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);
 		UDP_INC_STATS_BH(UDP_MIB_INERRORS);
 		kfree_skb(skb);
 		return -1;