From 6ce9e7b5fe3195d1ae6e3a0753d4ddcac5cd699e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 2 Sep 2009 18:05:33 -0700 Subject: ip: Report qdisc packet drops Christoph Lameter pointed out that packet drops at qdisc level where not accounted in SNMP counters. Only if application sets IP_RECVERR, drops are reported to user (-ENOBUFS errors) and SNMP counters updated. IP_RECVERR is used to enable extended reliable error message passing, but these are not needed to update system wide SNMP stats. This patch changes things a bit to allow SNMP counters to be updated, regardless of IP_RECVERR being set or not on the socket. Example after an UDP tx flood # netstat -s ... IP: 1487048 outgoing packets dropped ... Udp: ... SndbufErrors: 1487048 send() syscalls, do however still return an OK status, to not break applications. Note : send() manual page explicitly says for -ENOBUFS error : "The output queue for a network interface was full. This generally indicates that the interface has stopped sending, but may be caused by transient congestion. (Normally, this does not occur in Linux. Packets are just silently dropped when a device queue overflows.) " This is not true for IP_RECVERR enabled sockets : a send() syscall that hit a qdisc drop returns an ENOBUFS error. Many thanks to Christoph, David, and last but not least, Alexey ! Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/ip_output.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/ip_output.c') diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 7d0821054729..afae0cbabbf9 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1302,7 +1302,7 @@ int ip_push_pending_frames(struct sock *sk) err = ip_local_out(skb); if (err) { if (err > 0) - err = inet->recverr ? net_xmit_errno(err) : 0; + err = net_xmit_errno(err); if (err) goto error; } -- cgit v1.2.3