linux/net/ipv4
Ilpo Järvinen 77722b177a tcp: fix retrans_stamp advancing in error cases
It can happen, that tcp_retransmit_skb fails due to some error.
In such cases we might end up into a state where tp->retrans_out
is zero but that's only because we removed the TCPCB_SACKED_RETRANS
bit from a segment but couldn't retransmit it because of the error
that happened. Therefore some assumptions that retrans_out checks
are based do not necessarily hold, as there still can be an old
retransmission but that is only visible in TCPCB_EVER_RETRANS bit.
As retransmission happen in sequential order (except for some very
rare corner cases), it's enough to check the head skb for that bit.

Main reason for all this complexity is the fact that connection dying
time now depends on the validity of the retrans_stamp, in particular,
that successive retransmissions of a segment must not advance
retrans_stamp under any conditions. It seems after quick thinking that
this has relatively low impact as eventually TCP will go into CA_Loss
and either use the existing check for !retrans_stamp case or send a
retransmission successfully, setting a new base time for the dying
timer (can happen only once). At worst, the dying time will be
approximately the double of the intented time. In addition,
tcp_packet_delayed() will return wrong result (has some cc aspects
but due to rarity of these errors, it's hardly an issue).

One of retrans_stamp clearing happens indirectly through first going
into CA_Open state and then a later ACK lets the clearing to happen.
Thus tcp_try_keep_open has to be modified too.

Thanks to Damian Lukowski <damian@tvk.rwth-aachen.de> for hinting
that this possibility exists (though the particular case discussed
didn't after all have it happening but was just a debug patch
artifact).

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-12-08 20:56:12 -08:00
..
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
af_inet.c net: check kern before calling security subsystem 2009-11-05 22:18:18 -08:00
ah4.c xfrm: Use the user specified truncation length in ESP and AH 2009-11-25 15:48:41 -08:00
arp.c sysctl net: Remove unused binary sysctl code 2009-11-12 02:05:06 -08:00
cipso_ipv4.c ipv4: Define cipso_v4_delopt static 2009-10-07 14:45:58 -07:00
datagram.c inet: rename some inet_sock fields 2009-10-18 18:52:53 -07:00
devinet.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
esp4.c xfrm: Use the user specified truncation length in ESP and AH 2009-11-25 15:48:41 -08:00
fib_frontend.c ipv4 05/05: add sysctl to accept packets with local source addresses 2009-12-03 12:14:38 -08:00
fib_hash.c ipv4: fib table algorithm performance improvement 2009-10-05 00:21:56 -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: Allow fib_rule_unregister to batch 2009-12-03 12:22:55 -08:00
fib_semantics.c net: use net_eq to compare nets 2009-11-25 15:14:13 -08:00
fib_trie.c ipv4: fib table algorithm performance improvement 2009-10-05 00:21:56 -07:00
icmp.c icmp: icmp_send() can avoid a dev_put() 2009-11-01 23:55:10 -08:00
igmp.c net: Move && and || to end of previous line 2009-11-29 16:55:45 -08:00
inet_connection_sock.c TCPCT part 1a: add request_values parameter for sending SYNACK 2009-12-02 22:07:23 -08:00
inet_diag.c inet: rename some inet_sock fields 2009-10-18 18:52:53 -07:00
inet_fragment.c inet fragments: fix sparse warning: context imbalance 2009-02-26 23:13:35 -08:00
inet_hashtables.c tcp: Fix a connect() race with timewait sockets 2009-12-08 20:17:51 -08:00
inet_lro.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
inet_timewait_sock.c [PATCH] tcp: documents timewait refcnt tricks 2009-12-08 20:19:53 -08:00
inetpeer.c inetpeer: Optimize inet_getid() 2009-11-13 20:46:58 -08:00
ip_forward.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
ip_fragment.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
ip_gre.c net: Simplify ip_gre pernet operations. 2009-12-01 16:15:57 -08:00
ip_input.c net: use net_eq to compare nets 2009-11-25 15:14:13 -08:00
ip_options.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
ip_output.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-12-01 22:13:38 -08:00
ip_sockglue.c net: Cleanup redundant tests on unsigned 2009-10-29 01:39:54 -07:00
ipcomp.c net: constify struct net_protocol 2009-09-14 17:03:01 -07:00
ipconfig.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
ipip.c net: Simplify ipip pernet operations. 2009-12-01 16:15:58 -08:00
ipmr.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-11-17 00:05:02 -08:00
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 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
proc.c snmp: add missing counters for RFC 4293 2009-04-27 02:45:02 -07:00
protocol.c net: constify struct net_protocol 2009-09-14 17:03:01 -07:00
raw.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-10-29 21:28:59 -07:00
route.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
syncookies.c TCPCT part 1g: Responder Cookie => Initiator 2009-12-02 22:07:26 -08:00
sysctl_net_ipv4.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
tcp_bic.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_cong.c Networking: use CAP_NET_ADMIN when deciding to call request_module 2009-08-14 11:18:34 +10:00
tcp_cubic.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_diag.c tcp: diag: Dont report negative values for rx queue 2009-12-03 16:06:13 -08:00
tcp_highspeed.c [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp_htcp.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -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]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp_input.c tcp: fix retrans_stamp advancing in error cases 2009-12-08 20:56:12 -08:00
tcp_ipv4.c tcp: Fix a connect() race with timewait sockets 2009-12-08 20:17:51 -08:00
tcp_lp.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp_minisocks.c TCPCT part 1g: Responder Cookie => Initiator 2009-12-02 22:07:26 -08:00
tcp_output.c tcp: sysctl_tcp_cookie_size needs to be exported to modules. 2009-12-02 22:18:58 -08:00
tcp_probe.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp_scalable.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_timer.c tcp: Stalling connections: Move timeout calculation routine 2009-12-08 20:56:11 -08:00
tcp_vegas.c tcp: tcp_vegas ssthresh bugfix 2009-05-25 22:44:59 -07:00
tcp_vegas.h [TCP]: congestion control API pass RTT in microseconds 2007-07-31 02:27:57 -07:00
tcp_veno.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp_westwood.c [TCP]: congestion control API pass RTT in microseconds 2007-07-31 02:27:57 -07:00
tcp_yeah.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp.c tcp: Remove runtime check that can never be true. 2009-12-08 20:07:54 -08:00
tunnel4.c net: constify struct net_protocol 2009-09-14 17:03:01 -07:00
udp_impl.h net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
udp.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
udplite.c net: drop capability from protocol definitions 2009-11-05 21:40:17 -08:00
xfrm4_input.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
xfrm4_mode_beet.c ipsec: Interfamily IPSec BEET 2008-08-06 02:39:30 -07:00
xfrm4_mode_transport.c [IPSEC]: Use IPv6 calling convention as the convention for x->mode->output 2007-10-10 16:55:54 -07:00
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 sysctl net: Remove unused binary sysctl code 2009-11-12 02:05:06 -08:00
xfrm4_state.c xfrm: remove useless forward declarations 2008-11-25 01:05:54 -08:00
xfrm4_tunnel.c [IPCOMP]: Fix reception of incompressible packets 2008-01-31 19:27:24 -08:00