icmp: Account for ICMP out errors

When ip_append() fails because of socket limit or memory shortage,
increment ICMP_MIB_OUTERRORS counter, so that "netstat -s" can report
these errors.

LANG=C netstat -s | grep "ICMP messages failed"
    0 ICMP messages failed

For IPV6, implement ICMP6_MIB_OUTERRORS counter as well.

# grep Icmp6OutErrors /proc/net/dev_snmp6/*
/proc/net/dev_snmp6/eth0:Icmp6OutErrors                   	0
/proc/net/dev_snmp6/lo:Icmp6OutErrors                   	0
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/snmp.h

@@ -100,6 +100,7 @@ enum
 	ICMP6_MIB_INMSGS,			/* InMsgs */
 	ICMP6_MIB_INERRORS,			/* InErrors */
 	ICMP6_MIB_OUTMSGS,			/* OutMsgs */
+	ICMP6_MIB_OUTERRORS,			/* OutErrors */
 	__ICMP6_MIB_MAX
 };
 

net/ipv4/icmp.c

@@ -330,9 +330,10 @@ static void icmp_push_reply(struct icmp_bxm *icmp_param,
 	if (ip_append_data(sk, icmp_glue_bits, icmp_param,
 			   icmp_param->data_len+icmp_param->head_len,
 			   icmp_param->head_len,
-			   ipc, rt, MSG_DONTWAIT) < 0)
+			   ipc, rt, MSG_DONTWAIT) < 0) {
+		ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
 		ip_flush_pending_frames(sk);
-	else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
+	} else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 		struct icmphdr *icmph = icmp_hdr(skb);
 		__wsum csum = 0;
 		struct sk_buff *skb1;

net/ipv6/icmp.c

@@ -482,6 +482,7 @@ void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
 			      np->tclass, NULL, &fl, (struct rt6_info*)dst,
 			      MSG_DONTWAIT);
 	if (err) {
+		ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTMSGS);
 		ip6_flush_pending_frames(sk);
 		goto out_put;
 	}
@@ -562,6 +563,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
 				(struct rt6_info*)dst, MSG_DONTWAIT);
 
 	if (err) {
+		ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTMSGS);
 		ip6_flush_pending_frames(sk);
 		goto out_put;
 	}

net/ipv6/proc.c

@@ -97,6 +97,7 @@ static const struct snmp_mib snmp6_icmp6_list[] = {
 	SNMP_MIB_ITEM("Icmp6InMsgs", ICMP6_MIB_INMSGS),
 	SNMP_MIB_ITEM("Icmp6InErrors", ICMP6_MIB_INERRORS),
 	SNMP_MIB_ITEM("Icmp6OutMsgs", ICMP6_MIB_OUTMSGS),
+	SNMP_MIB_ITEM("Icmp6OutErrors", ICMP6_MIB_OUTERRORS),
 	SNMP_MIB_SENTINEL
 };