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linux/net/ipv4
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Eric Dumazet 6ce9e7b5fe 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 <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-09-02 18:05:33 -07:00
..
netfilter netfilter: tcp conntrack: fix unacknowledged data detection with NAT 2009-06-29 14:07:56 +02:00
af_inet.c ipv4: af_inet.c cleanups 2009-08-28 23:45:21 -07:00
ah4.c netns xfrm: AH/ESP in netns! 2008-11-25 17:59:27 -08:00
arp.c net: make neigh_ops constant 2009-09-01 17:40:57 -07:00
cipso_ipv4.c netlabel: Label incoming TCP connections correctly in SELinux 2009-03-28 15:01:36 +11:00
datagram.c
devinet.c net: Fix devinet_sysctl_forward 2009-05-18 22:15:58 -07:00
esp4.c netns xfrm: AH/ESP in netns! 2008-11-25 17:59:27 -08:00
fib_frontend.c ipv4: cleanup: remove unnecessary include. 2009-05-18 15:16:38 -07:00
fib_hash.c ipv4: cleanup - remove two unused parameters from fib_semantic_match(). 2009-05-18 15:16:37 -07:00
fib_lookup.h ipv4: cleanup - remove two unused parameters from fib_semantic_match(). 2009-05-18 15:16:37 -07:00
fib_rules.c net: Remove unused parameter from fill method in fib_rules_ops. 2009-05-20 17:26:23 -07:00
fib_semantics.c ipv4: cleanup - remove two unused parameters from fib_semantic_match(). 2009-05-18 15:16:37 -07:00
fib_trie.c fib_trie: resize rework 2009-08-28 23:57:15 -07:00
icmp.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
igmp.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
inet_connection_sock.c net: move bsockets outside of read only beginning of struct inet_hashinfo 2009-02-01 12:31:33 -08:00
inet_diag.c net: correct off-by-one write allocations reports 2009-06-18 00:29:12 -07:00
inet_fragment.c inet fragments: fix sparse warning: context imbalance 2009-02-26 23:13:35 -08:00
inet_hashtables.c net: move bsockets outside of read only beginning of struct inet_hashinfo 2009-02-01 12:31:33 -08:00
inet_lro.c include/net net/ - csum_partial - remove unnecessary casts 2008-11-19 15:44:53 -08:00
inet_timewait_sock.c tcp: fix premature termination of FIN_WAIT2 time-wait sockets 2009-08-29 00:00:35 -07:00
inetpeer.c net: clean up net/ipv4/ah4.c esp4.c fib_semantics.c inet_connection_sock.c inetpeer.c ip_output.c 2008-11-03 00:23:42 -08:00
ip_forward.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
ip_fragment.c ipv4: Use frag list abstraction interfaces. 2009-06-09 00:19:37 -07:00
ip_gre.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-09-02 00:32:56 -07:00
ip_input.c inet: Call skb_orphan before tproxy activates 2009-06-26 19:22:37 -07:00
ip_options.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
ip_output.c ip: Report qdisc packet drops 2009-09-02 18:05:33 -07:00
ip_sockglue.c net: skb->rtable accessor 2009-06-03 02:51:02 -07:00
ipcomp.c netns xfrm: state lookup in netns 2008-11-25 17:30:50 -08:00
ipconfig.c ipv4: teach ipconfig about the MTU option in DHCP 2009-05-19 15:36:17 -07:00
ipip.c netdev: convert pseudo-devices to netdev_tx_t 2009-09-01 01:13:07 -07:00
ipmr.c netdev: convert pseudo-devices to netdev_tx_t 2009-09-01 01:13:07 -07:00
Kconfig ipv4: update ARPD help text 2009-06-13 23:36:32 -07:00
Makefile IPVS: Move IPVS to net/netfilter/ipvs 2008-10-07 08:38:24 +11:00
netfilter.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
proc.c snmp: add missing counters for RFC 4293 2009-04-27 02:45:02 -07:00
protocol.c
raw.c ip: Report qdisc packet drops 2009-09-02 18:05:33 -07:00
route.c net: ip_rt_send_redirect() optimization 2009-08-28 23:52:01 -07:00
syncookies.c syncookies: remove last_synq_overflow from struct tcp_sock 2009-04-20 02:25:26 -07:00
sysctl_net_ipv4.c net: '&' redux 2008-11-03 18:21:05 -08:00
tcp_bic.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_cong.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_cubic.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_diag.c net: inet_diag_handler structs can be const 2008-11-19 15:43:27 -08:00
tcp_highspeed.c
tcp_htcp.c htcp: merge icsk_ca_state compare 2009-03-02 03:00:14 -08:00
tcp_hybla.c tcp: Fix tcp_hybla zero congestion window growth with small rho and large cwnd. 2008-10-07 15:58:17 -07:00
tcp_illinois.c
tcp_input.c Revert Backoff [v3]: Revert RTO on ICMP destination unreachable 2009-09-01 02:45:42 -07:00
tcp_ipv4.c inet: inet_connection_sock_af_ops const 2009-09-02 01:03:49 -07:00
tcp_lp.c
tcp_minisocks.c tcp: Remove redundant copy of MD5 authentication key 2009-08-29 00:19:25 -07:00
tcp_output.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-07-23 19:03:51 -07:00
tcp_probe.c tcp: '< 0' test on unsigned 2009-03-13 16:05:14 -07:00
tcp_scalable.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_timer.c Revert Backoff [v3]: Calculate TCP's connection close threshold as a time value. 2009-09-01 02:45:47 -07:00
tcp_vegas.c tcp: tcp_vegas ssthresh bugfix 2009-05-25 22:44:59 -07:00
tcp_vegas.h
tcp_veno.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_westwood.c
tcp_yeah.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp.c tcp: keepalive cleanups 2009-08-28 23:48:54 -07:00
tunnel4.c
udp_impl.h udp: introduce struct udp_table and multiple spinlocks 2008-10-29 01:41:45 -07:00
udp.c ip: Report qdisc packet drops 2009-09-02 18:05:33 -07:00
udplite.c udp: RCU handling for Unicast packets. 2008-10-29 02:11:14 -07:00
xfrm4_input.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
xfrm4_mode_beet.c
xfrm4_mode_transport.c
xfrm4_mode_tunnel.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
xfrm4_output.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
xfrm4_policy.c xfrm4: fix build when SYSCTLs are disabled 2009-08-04 20:18:33 -07:00
xfrm4_state.c xfrm: remove useless forward declarations 2008-11-25 01:05:54 -08:00
xfrm4_tunnel.c