linux-stable.git/net/ipv4/tcp_timer.c, branch v4.9.26 Linux kernel stable tree tcp: fix various issues for sockets morphing to listen state 2017-03-22T11:43:33+00:00 Eric Dumazet edumazet@google.com 2017-03-03T22:08:21+00:00 07753bc6a2816c1c3b9f7bff133251f623c7bc91 [ Upstream commit 02b2faaf0af1d85585f6d6980e286d53612acfc2 ] Dmitry Vyukov reported a divide by 0 triggered by syzkaller, exploiting tcp_disconnect() path that was never really considered and/or used before syzkaller ;) I was not able to reproduce the bug, but it seems issues here are the three possible actions that assumed they would never trigger on a listener. 1) tcp_write_timer_handler 2) tcp_delack_timer_handler 3) MTU reduction Only IPv6 MTU reduction was properly testing TCP_CLOSE and TCP_LISTEN states from tcp_v6_mtu_reduced() Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 02b2faaf0af1d85585f6d6980e286d53612acfc2 ]

Dmitry Vyukov reported a divide by 0 triggered by syzkaller, exploiting
tcp_disconnect() path that was never really considered and/or used
before syzkaller ;)

I was not able to reproduce the bug, but it seems issues here are the
three possible actions that assumed they would never trigger on a
listener.

1) tcp_write_timer_handler
2) tcp_delack_timer_handler
3) MTU reduction

Only IPv6 MTU reduction was properly testing TCP_CLOSE and TCP_LISTEN
 states from tcp_v6_mtu_reduced()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: Change txhash on every SYN and RTO retransmit 2016-09-28T11:52:34+00:00 Lawrence Brakmo brakmo@fb.com 2016-09-28T02:03:37+00:00 3acf3ec3f4b0fd4263989f2e4227bbd1c42b5fe1 The current code changes txhash (flowlables) on every retransmitted SYN/ACK, but only after the 2nd retransmitted SYN and only after tcp_retries1 RTO retransmits. With this patch: 1) txhash is changed with every SYN retransmits 2) txhash is changed with every RTO. The result is that we can start re-routing around failed (or very congested paths) as soon as possible. Otherwise application health checks may fail and the connection may be terminated before we start to change txhash. v4: Removed sysctl, txhash is changed for all RTOs v3: Removed text saying default value of sysctl is 0 (it is 100) v2: Added sysctl documentation and cleaned code Tested with packetdrill tests Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The current code changes txhash (flowlables) on every retransmitted
SYN/ACK, but only after the 2nd retransmitted SYN and only after
tcp_retries1 RTO retransmits.

With this patch:
1) txhash is changed with every SYN retransmits
2) txhash is changed with every RTO.

The result is that we can start re-routing around failed (or very
congested paths) as soon as possible. Otherwise application health
checks may fail and the connection may be terminated before we start
to change txhash.

v4: Removed sysctl, txhash is changed for all RTOs
v3: Removed text saying default value of sysctl is 0 (it is 100)
v2: Added sysctl documentation and cleaned code

Tested with packetdrill tests

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: properly account Fast Open SYN-ACK retrans 2016-09-22T07:33:01+00:00 Yuchung Cheng ycheng@google.com 2016-09-21T23:16:15+00:00 7e32b44361abc77fbc01f2b97b045c405b2583e5 Since the TFO socket is accepted right off SYN-data, the socket owner can call getsockopt(TCP_INFO) to collect ongoing SYN-ACK retransmission or timeout stats (i.e., tcpi_total_retrans, tcpi_retransmits). Currently those stats are only updated upon handshake completes. This patch fixes it. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Since the TFO socket is accepted right off SYN-data, the socket
owner can call getsockopt(TCP_INFO) to collect ongoing SYN-ACK
retransmission or timeout stats (i.e., tcpi_total_retrans,
tcpi_retransmits). Currently those stats are only updated
upon handshake completes. This patch fixes it.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp_timer.c: Add kernel-doc function descriptions 2016-07-16T06:18:14+00:00 Richard Sailer richard@weltraumpflege.org 2016-07-16T02:04:34+00:00 c380d37e97e783e36a924279fbd2f6837508546a This adds kernel-doc style descriptions for 6 functions and fixes 1 typo. Signed-off-by: Richard Sailer <richard@weltraumpflege.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
This adds kernel-doc style descriptions for 6 functions and
fixes 1 typo.

Signed-off-by: Richard Sailer <richard@weltraumpflege.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: do not assume TCP code is non preemptible 2016-05-02T21:02:25+00:00 Eric Dumazet edumazet@google.com 2016-04-29T21:16:47+00:00 c10d9310edf5aa4a676991139d1a43ec7d87e56b We want to to make TCP stack preemptible, as draining prequeue and backlog queues can take lot of time. Many SNMP updates were assuming that BH (and preemption) was disabled. Need to convert some __NET_INC_STATS() calls to NET_INC_STATS() and some __TCP_INC_STATS() to TCP_INC_STATS() Before using this_cpu_ptr(net->ipv4.tcp_sk) in tcp_v4_send_reset() and tcp_v4_send_ack(), we add an explicit preempt disabled section. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
We want to to make TCP stack preemptible, as draining prequeue
and backlog queues can take lot of time.

Many SNMP updates were assuming that BH (and preemption) was disabled.

Need to convert some __NET_INC_STATS() calls to NET_INC_STATS()
and some __TCP_INC_STATS() to TCP_INC_STATS()

Before using this_cpu_ptr(net->ipv4.tcp_sk) in tcp_v4_send_reset()
and tcp_v4_send_ack(), we add an explicit preempt disabled section.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: rename NET_{ADD|INC}_STATS_BH() 2016-04-28T02:48:24+00:00 Eric Dumazet edumazet@google.com 2016-04-27T23:44:39+00:00 02a1d6e7a6bb025a77da77012190e1efc1970f1c Rename NET_INC_STATS_BH() to __NET_INC_STATS() and NET_ADD_STATS_BH() to __NET_ADD_STATS() Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Rename NET_INC_STATS_BH() to __NET_INC_STATS()
and NET_ADD_STATS_BH() to __NET_ADD_STATS()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp-tso: do not split TSO packets at retransmit time 2016-04-24T18:43:59+00:00 Eric Dumazet edumazet@google.com 2016-04-21T17:55:23+00:00 10d3be569243def8d92ac3722395ef5a59c504e6 Linux TCP stack painfully segments all TSO/GSO packets before retransmits. This was fine back in the days when TSO/GSO were emerging, with their bugs, but we believe the dark age is over. Keeping big packets in write queues, but also in stack traversal has a lot of benefits. - Less memory overhead, because write queues have less skbs - Less cpu overhead at ACK processing. - Better SACK processing, as lot of studies mentioned how awful linux was at this ;) - Less cpu overhead to send the rtx packets (IP stack traversal, netfilter traversal, drivers...) - Better latencies in presence of losses. - Smaller spikes in fq like packet schedulers, as retransmits are not constrained by TCP Small Queues. 1 % packet losses are common today, and at 100Gbit speeds, this translates to ~80,000 losses per second. Losses are often correlated, and we see many retransmit events leading to 1-MSS train of packets, at the time hosts are already under stress. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Linux TCP stack painfully segments all TSO/GSO packets before retransmits.

This was fine back in the days when TSO/GSO were emerging, with their
bugs, but we believe the dark age is over.

Keeping big packets in write queues, but also in stack traversal
has a lot of benefits.
 - Less memory overhead, because write queues have less skbs
 - Less cpu overhead at ACK processing.
 - Better SACK processing, as lot of studies mentioned how
   awful linux was at this ;)
 - Less cpu overhead to send the rtx packets
   (IP stack traversal, netfilter traversal, drivers...)
 - Better latencies in presence of losses.
 - Smaller spikes in fq like packet schedulers, as retransmits
   are not constrained by TCP Small Queues.

1 % packet losses are common today, and at 100Gbit speeds, this
translates to ~80,000 losses per second.
Losses are often correlated, and we see many retransmit events
leading to 1-MSS train of packets, at the time hosts are already
under stress.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp_orphan_retries sysctl knob 2016-02-07T19:35:11+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:55+00:00 c402d9beffb6141ab2e4d2ad8be71128803a28ca Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp_retries2 sysctl knob 2016-02-07T19:35:11+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:54+00:00 c6214a97c86c660de4f7ddb8eed925192e646161 Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp_retries1 sysctl knob 2016-02-07T19:35:10+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:53+00:00 ae5c3f406cffe15ffd2aa544961b7cd027468d46 Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>