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* net: sock: introduce sk_error_reportAlexander Aring2021-06-291-1/+1
| | | | | | | | | This patch introduces a function wrapper to call the sk_error_report callback. That will prepare to add additional handling whenever sk_error_report is called, for example to trace socket errors. Signed-off-by: Alexander Aring <aahringo@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* ipv4: Fix spelling mistakesZheng Yongjun2021-06-071-2/+2
| | | | | | | | | | | | Fix some spelling mistakes in comments: Dont ==> Don't timout ==> timeout incomming ==> incoming necesarry ==> necessary substract ==> subtract Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: make TCP_USER_TIMEOUT accurate for zero window probesEnke Chen2021-01-231-0/+18
| | | | | | | | | | | | | | | | | | | | The TCP_USER_TIMEOUT is checked by the 0-window probe timer. As the timer has backoff with a max interval of about two minutes, the actual timeout for TCP_USER_TIMEOUT can be off by up to two minutes. In this patch the TCP_USER_TIMEOUT is made more accurate by taking it into account when computing the timer value for the 0-window probes. This patch is similar to and builds on top of the one that made TCP_USER_TIMEOUT accurate for RTOs in commit b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout() helper to improve accuracy"). Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT") Signed-off-by: Enke Chen <enchen@paloaltonetworks.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20210122191306.GA99540@localhost.localdomain Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* tcp: fix TCP socket rehash stats mis-accountingYuchung Cheng2021-01-191-14/+8
| | | | | | | | | | | | | | | | | | | | | | The previous commit 32efcc06d2a1 ("tcp: export count for rehash attempts") would mis-account rehashing SNMP and socket stats: a. During handshake of an active open, only counts the first SYN timeout b. After handshake of passive and active open, stop updating after (roughly) TCP_RETRIES1 recurring RTOs c. After the socket aborts, over count timeout_rehash by 1 This patch fixes this by checking the rehash result from sk_rethink_txhash. Fixes: 32efcc06d2a1 ("tcp: export count for rehash attempts") Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Link: https://lore.kernel.org/r/20210119192619.1848270-1-ycheng@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* tcp: fix TCP_USER_TIMEOUT with zero windowEnke Chen2021-01-181-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The TCP session does not terminate with TCP_USER_TIMEOUT when data remain untransmitted due to zero window. The number of unanswered zero-window probes (tcp_probes_out) is reset to zero with incoming acks irrespective of the window size, as described in tcp_probe_timer(): RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as long as the receiver continues to respond probes. We support this by default and reset icsk_probes_out with incoming ACKs. This counter, however, is the wrong one to be used in calculating the duration that the window remains closed and data remain untransmitted. Thanks to Jonathan Maxwell <jmaxwell37@gmail.com> for diagnosing the actual issue. In this patch a new timestamp is introduced for the socket in order to track the elapsed time for the zero-window probes that have not been answered with any non-zero window ack. Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT") Reported-by: William McCall <william.mccall@gmail.com> Co-developed-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Enke Chen <enchen@paloaltonetworks.com> Reviewed-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20210115223058.GA39267@localhost.localdomain Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* inet: remove icsk_ack.blockedEric Dumazet2020-09-301-1/+0
| | | | | | | | | | | | | | | TCP has been using it to work around the possibility of tcp_delack_timer() finding the socket owned by user. After commit 6f458dfb4092 ("tcp: improve latencies of timer triggered events") we added TCP_DELACK_TIMER_DEFERRED atomic bit for more immediate recovery, so we can get rid of icsk_ack.blocked This frees space that following patch will reuse. 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: ipv4: kerneldoc fixesAndrew Lunn2020-07-131-1/+1
| | | | | | | | | | | Simple fixes which require no deep knowledge of the code. Cc: Paul Moore <paul@paul-moore.com> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Andrew Lunn <andrew@lunn.ch> Acked-by: Paul Moore <paul@paul-moore.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: add tp->dup_ack_counterEric Dumazet2020-04-301-1/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In commit 86de5921a3d5 ("tcp: defer SACK compression after DupThresh") I added a TCP_FASTRETRANS_THRESH bias to tp->compressed_ack in order to enable sack compression only after 3 dupacks. Since we plan to relax this rule for flows that involve stacks not requiring this old rule, this patch adds a distinct tp->dup_ack_counter. This means the TCP_FASTRETRANS_THRESH value is now used in a single location that a future patch can adjust: if (tp->dup_ack_counter < TCP_FASTRETRANS_THRESH) { tp->dup_ack_counter++; goto send_now; } This patch also introduces tcp_sack_compress_send_ack() helper to ease following patch comprehension. This patch refines LINUX_MIB_TCPACKCOMPRESSED to not count the acks that we had to send if the timer expires or tcp_sack_compress_send_ack() is sending an ack. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: export count for rehash attemptsAbdul Kabbani2020-01-261-0/+6
| | | | | | | | | | | | | | | | | | | | | | Using IPv6 flow-label to swiftly route around avoid congested or disconnected network path can greatly improve TCP reliability. This patch adds SNMP counters and a OPT_STATS counter to track both host-level and connection-level statistics. Network administrators can use these counters to evaluate the impact of this new ability better. Export count for rehash attempts to 1) two SNMP counters: TcpTimeoutRehash (rehash due to timeouts), and TcpDuplicateDataRehash (rehash due to receiving duplicate packets) 2) Timestamping API SOF_TIMESTAMPING_OPT_STATS. Signed-off-by: Abdul Kabbani <akabbani@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Kevin(Yudong) Yang <yyd@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: refactor tcp_retransmit_timer()Eric Dumazet2019-12-031-2/+8
| | | | | | | | | | | | | | | | It appears linux-4.14 stable needs a backport of commit 88f8598d0a30 ("tcp: exit if nothing to retransmit on RTO timeout") Since tcp_rtx_queue_empty() is not in pre 4.15 kernels, let's refactor tcp_retransmit_timer() to only use tcp_rtx_queue_head() I will provide to stable teams the squashed patches. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: add rcu protection around tp->fastopen_rskEric Dumazet2019-10-131-5/+6
| | | | | | | | | | | | | | | | | | Both tcp_v4_err() and tcp_v6_err() do the following operations while they do not own the socket lock : fastopen = tp->fastopen_rsk; snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una; The problem is that without appropriate barrier, the compiler might reload tp->fastopen_rsk and trigger a NULL deref. request sockets are protected by RCU, we can simply add the missing annotations and barriers to solve the issue. Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: adjust rto_base in retransmits_timed_out()Eric Dumazet2019-10-011-2/+7
| | | | | | | | | | | | | | | | | | | The cited commit exposed an old retransmits_timed_out() bug which assumed it could call tcp_model_timeout() with TCP_RTO_MIN as rto_base for all states. But flows in SYN_SENT or SYN_RECV state uses a different RTO base (1 sec instead of 200 ms, unless BPF choses another value) This caused a reduction of SYN retransmits from 6 to 4 with the default /proc/sys/net/ipv4/tcp_syn_retries value. Fixes: a41e8a88b06e ("tcp: better handle TCP_USER_TIMEOUT in SYN_SENT state") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Marek Majkowski <marek@cloudflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: better handle TCP_USER_TIMEOUT in SYN_SENT stateEric Dumazet2019-09-271-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Yuchung Cheng and Marek Majkowski independently reported a weird behavior of TCP_USER_TIMEOUT option when used at connect() time. When the TCP_USER_TIMEOUT is reached, tcp_write_timeout() believes the flow should live, and the following condition in tcp_clamp_rto_to_user_timeout() programs one jiffie timers : remaining = icsk->icsk_user_timeout - elapsed; if (remaining <= 0) return 1; /* user timeout has passed; fire ASAP */ This silly situation ends when the max syn rtx count is reached. This patch makes sure we honor both TCP_SYNCNT and TCP_USER_TIMEOUT, avoiding these spurious SYN packets. Fixes: b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout() helper to improve accuracy") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Yuchung Cheng <ycheng@google.com> Reported-by: Marek Majkowski <marek@cloudflare.com> Cc: Jon Maxwell <jmaxwell37@gmail.com> Link: https://marc.info/?l=linux-netdev&m=156940118307949&w=2 Acked-by: Jon Maxwell <jmaxwell37@gmail.com> Tested-by: Marek Majkowski <marek@cloudflare.com> Signed-off-by: Marek Majkowski <marek@cloudflare.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: add new tcp_mtu_probe_floor sysctlJosh Hunt2019-08-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | The current implementation of TCP MTU probing can considerably underestimate the MTU on lossy connections allowing the MSS to get down to 48. We have found that in almost all of these cases on our networks these paths can handle much larger MTUs meaning the connections are being artificially limited. Even though TCP MTU probing can raise the MSS back up we have seen this not to be the case causing connections to be "stuck" with an MSS of 48 when heavy loss is present. Prior to pushing out this change we could not keep TCP MTU probing enabled b/c of the above reasons. Now with a reasonble floor set we've had it enabled for the past 6 months. The new sysctl will still default to TCP_MIN_SND_MSS (48), but gives administrators the ability to control the floor of MSS probing. Signed-off-by: Josh Hunt <johunt@akamai.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: enforce tcp_min_snd_mss in tcp_mtu_probing()Eric Dumazet2019-06-151-0/+1
| | | | | | | | | | | | | | | | | | | If mtu probing is enabled tcp_mtu_probing() could very well end up with a too small MSS. Use the new sysctl tcp_min_snd_mss to make sure MSS search is performed in an acceptable range. CVE-2019-11479 -- tcp mss hardcoded to 48 Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Jonathan Lemon <jonathan.lemon@gmail.com> Cc: Jonathan Looney <jtl@netflix.com> Acked-by: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Bruce Curtis <brucec@netflix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* treewide: Add SPDX license identifier for missed filesThomas Gleixner2019-05-211-0/+1
| | | | | | | | | | | | | | | | | Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tcp: lower congestion window on Fast Open SYNACK timeoutYuchung Cheng2019-05-011-0/+3
| | | | | | | | | | | | | | | | | | TCP sender would use congestion window of 1 packet on the second SYN and SYNACK timeout except passive TCP Fast Open. This makes passive TFO too aggressive and unfair during congestion at handshake. This patch fixes this issue so TCP (fast open or not, passive or active) always conforms to the RFC6298. Note that tcp_enter_loss() is called only once during recurring timeouts. This is because during handshake, high_seq and snd_una are the same so tcp_enter_loss() would incorrect set the undo state variables multiple times. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Refactor pingpong codeWei Wang2019-01-271-2/+2
| | | | | | | | | | | | | | | Instead of using pingpong as a single bit information, we refactor the code to treat it as a counter. When interactive session is detected, we set pingpong count to TCP_PINGPONG_THRESH. And when pingpong count is >= TCP_PINGPONG_THRESH, we consider the session in pingpong mode. This patch is a pure refactor and sets foundation for the next patch. This patch itself does not change any pingpong logic. Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: retry more conservatively on local congestionYuchung Cheng2019-01-171-5/+3
| | | | | | | | | | | | | | | | | | | | | | | | Previously when the sender fails to retransmit a data packet on timeout due to congestion in the local host (e.g. throttling in qdisc), it'll retry within an RTO up to 500ms. In low-RTT networks such as data-centers, RTO is often far below the default minimum 200ms (and the cap 500ms). Then local host congestion could trigger a retry storm pouring gas to the fire. Worse yet, the retry counter (icsk_retransmits) is not properly updated so the aggressive retry may exceed the system limit (15 rounds) until the packet finally slips through. On such rare events, it's wise to retry more conservatively (500ms) and update the stats properly to reflect these incidents and follow the system limit. Note that this is consistent with the behavior when a keep-alive probe is dropped due to local congestion. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: simplify window probe aborting on USER_TIMEOUTYuchung Cheng2019-01-171-7/+7
| | | | | | | | | | | | | | | | Previously we use the next unsent skb's timestamp to determine when to abort a socket stalling on window probes. This no longer works as skb timestamp reflects the last instead of the first transmission. Instead we can estimate how long the socket has been stalling with the probe count and the exponential backoff behavior. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: create a helper to model exponential backoffYuchung Cheng2019-01-171-13/+18
| | | | | | | | | | | Create a helper to model TCP exponential backoff for the next patch. This is pure refactor w no behavior change. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: properly track retry time on passive Fast OpenYuchung Cheng2019-01-171-0/+3
| | | | | | | | | | | | | | | | | This patch addresses a corner issue on timeout behavior of a passive Fast Open socket. A passive Fast Open server may write and close the socket when it is re-trying SYN-ACK to complete the handshake. After the handshake is completely, the server does not properly stamp the recovery start time (tp->retrans_stamp is 0), and the socket may abort immediately on the very first FIN timeout, instead of retying until it passes the system or user specified limit. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: always set retrans_stamp on recoveryYuchung Cheng2019-01-171-20/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | Previously TCP socket's retrans_stamp is not set if the retransmission has failed to send. As a result if a socket is experiencing local issues to retransmit packets, determining when to abort a socket is complicated w/o knowning the starting time of the recovery since retrans_stamp may remain zero. This complication causes sub-optimal behavior that TCP may use the latest, instead of the first, retransmission time to compute the elapsed time of a stalling connection due to local issues. Then TCP may disrecard TCP retries settings and keep retrying until it finally succeed: not a good idea when the local host is already strained. The simple fix is to always timestamp the start of a recovery. It's worth noting that retrans_stamp is also used to compare echo timestamp values to detect spurious recovery. This patch does not break that because retrans_stamp is still later than when the original packet was sent. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: exit if nothing to retransmit on RTO timeoutYuchung Cheng2019-01-171-4/+2
| | | | | | | | | | | | | Previously TCP only warns if its RTO timer fires and the retransmission queue is empty, but it'll cause null pointer reference later on. It's better to avoid such catastrophic failure and simply exit with a warning. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: change txhash on SYN-data timeoutYuchung Cheng2019-01-101-1/+1
| | | | | | | | | | | | | | | | | Previously upon SYN timeouts the sender recomputes the txhash to try a different path. However this does not apply on the initial timeout of SYN-data (active Fast Open). Therefore an active IPv6 Fast Open connection may incur one second RTO penalty to take on a new path after the second SYN retransmission uses a new flow label. This patch removes this undesirable behavior so Fast Open changes the flow label just like the regular connections. This also helps avoid falsely disabling Fast Open on the sender which triggers after two consecutive SYN timeouts on Fast Open. Signed-off-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: fix SNMP TCP timeout under-estimationYuchung Cheng2018-11-301-4/+4
| | | | | | | | | | | | | | | | | Previously the SNMP TCPTIMEOUTS counter has inconsistent accounting: 1. It counts all SYN and SYN-ACK timeouts 2. It counts timeouts in other states except recurring timeouts and timeouts after fast recovery or disorder state. Such selective accounting makes analysis difficult and complicated. For example the monitoring system needs to collect many other SNMP counters to infer the total amount of timeout events. This patch makes TCPTIMEOUTS counter simply counts all the retransmit timeout (SYN or data or FIN). 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: David S. Miller <davem@davemloft.net>
* tcp: fix off-by-one bug on aborting window-probing socketYuchung Cheng2018-11-301-1/+1
| | | | | | | | | | | Previously there is an off-by-one bug on determining when to abort a stalled window-probing socket. This patch fixes that so it is consistent with tcp_write_timeout(). 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: David S. Miller <davem@davemloft.net>
* tcp: address problems caused by EDT misshapsEric Dumazet2018-11-241-4/+6
| | | | | | | | | | | | | | | | | When a qdisc setup including pacing FQ is dismantled and recreated, some TCP packets are sent earlier than instructed by TCP stack. TCP can be fooled when ACK comes back, because the following operation can return a negative value. tcp_time_stamp(tp) - tp->rx_opt.rcv_tsecr; Some paths in TCP stack were not dealing properly with this, this patch addresses four of them. Fixes: ab408b6dc744 ("tcp: switch tcp and sch_fq to new earliest departure time model") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: defer SACK compression after DupThreshEric Dumazet2018-11-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Jean-Louis reported a TCP regression and bisected to recent SACK compression. After a loss episode (receiver not able to keep up and dropping packets because its backlog is full), linux TCP stack is sending a single SACK (DUPACK). Sender waits a full RTO timer before recovering losses. While RFC 6675 says in section 5, "Algorithm Details", (2) If DupAcks < DupThresh but IsLost (HighACK + 1) returns true -- indicating at least three segments have arrived above the current cumulative acknowledgment point, which is taken to indicate loss -- go to step (4). ... (4) Invoke fast retransmit and enter loss recovery as follows: there are old TCP stacks not implementing this strategy, and still counting the dupacks before starting fast retransmit. While these stacks probably perform poorly when receivers implement LRO/GRO, we should be a little more gentle to them. This patch makes sure we do not enable SACK compression unless 3 dupacks have been sent since last rcv_nxt update. Ideally we should even rearm the timer to send one or two more DUPACK if no more packets are coming, but that will be work aiming for linux-4.21. Many thanks to Jean-Louis for bisecting the issue, providing packet captures and testing this patch. Fixes: 5d9f4262b7ea ("tcp: add SACK compression") Reported-by: Jean-Louis Dupond <jean-louis@dupond.be> Tested-by: Jean-Louis Dupond <jean-louis@dupond.be> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: do not change tcp_wstamp_ns in tcp_mstamp_refreshEric Dumazet2018-10-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | In EDT design, I made the mistake of using tcp_wstamp_ns to store the last tcp_clock_ns() sample and to store the pacing virtual timer. This causes major regressions at high speed flows. Introduce tcp_clock_cache to store last tcp_clock_ns(). This is needed because some arches have slow high-resolution kernel time service. tcp_wstamp_ns is only updated when a packet is sent. Note that we can remove tcp_mstamp in the future since tcp_mstamp is essentially tcp_clock_cache/1000, so the apparent socket size increase is temporary. Fixes: 9799ccb0e984 ("tcp: add tcp_wstamp_ns socket field") 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>
* tcp/fq: move back to CLOCK_MONOTONICEric Dumazet2018-10-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | In the recent TCP/EDT patch series, I switched TCP and sch_fq clocks from MONOTONIC to TAI, in order to meet the choice done earlier for sch_etf packet scheduler. But sure enough, this broke some setups were the TAI clock jumps forward (by almost 50 year...), as reported by Leonard Crestez. If we want to converge later, we'll probably need to add an skb field to differentiate the clock bases, or a socket option. In the meantime, an UDP application will need to use CLOCK_MONOTONIC base for its SCM_TXTIME timestamps if using fq packet scheduler. Fixes: 72b0094f9182 ("tcp: switch tcp_clock_ns() to CLOCK_TAI base") Fixes: 142537e41923 ("net_sched: sch_fq: switch to CLOCK_TAI") Fixes: fd2bca2aa789 ("tcp: switch internal pacing timer to CLOCK_TAI") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Leonard Crestez <leonard.crestez@nxp.com> Tested-by: Leonard Crestez <leonard.crestez@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: switch internal pacing timer to CLOCK_TAIEric Dumazet2018-09-211-1/+1
| | | | | | | | Next patch will use tcp_wstamp_ns to feed internal TCP pacing timer, so switch to CLOCK_TAI to share same base. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: provide earliest departure time in skb->tstampEric Dumazet2018-09-211-1/+1
| | | | | | | | | | | | | | | | Switch internal TCP skb->skb_mstamp to skb->skb_mstamp_ns, from usec units to nsec units. Do not clear skb->tstamp before entering IP stacks in TX, so that qdisc or devices can implement pacing based on the earliest departure time instead of socket sk->sk_pacing_rate Packets are fed with tcp_wstamp_ns, and following patch will update tcp_wstamp_ns when both TCP and sch_fq switch to the earliest departure time mechanism. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: make function tcp_retransmit_stamp() staticWei Yongjun2018-07-251-1/+1
| | | | | | | | | | Fixes the following sparse warnings: net/ipv4/tcp_timer.c:25:5: warning: symbol 'tcp_retransmit_stamp' was not declared. Should it be static? Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Add tcp_clamp_rto_to_user_timeout() helper to improve accuracyJon Maxwell2018-07-211-1/+17
| | | | | | | | | | | | Create the tcp_clamp_rto_to_user_timeout() helper routine. To calculate the correct rto, so that the TCP_USER_TIMEOUT socket option is more accurate. Taking suggestions and feedback into account from Eric Dumazet, Neal Cardwell and David Laight. Due to the 1st commit we can avoid the msecs_to_jiffies() and jiffies_to_msecs() dance. Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Add tcp_retransmit_stamp() helper routineJon Maxwell2018-07-211-8/+17
| | | | | | | | | Create a seperate helper routine as per Neal Cardwells suggestion. To be used by the final commit in this series and retransmits_timed_out(). Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: convert icsk_user_timeout from jiffies to msecsJon Maxwell2018-07-211-4/+4
| | | | | | | | | | | This is a preparatory commit. Part of this series that improves the socket TCP_USER_TIMEOUT option accuracy. Implement Eric Dumazets idea to convert icsk->icsk_user_timeout from jiffies to msecs. To eliminate the msecs_to_jiffies() and jiffies_to_msecs() dance in future. Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: add SACK compressionEric Dumazet2018-05-181-0/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When TCP receives an out-of-order packet, it immediately sends a SACK packet, generating network load but also forcing the receiver to send 1-MSS pathological packets, increasing its RTX queue length/depth, and thus processing time. Wifi networks suffer from this aggressive behavior, but generally speaking, all these SACK packets add fuel to the fire when networks are under congestion. This patch adds a high resolution timer and tp->compressed_ack counter. Instead of sending a SACK, we program this timer with a small delay, based on RTT and capped to 1 ms : delay = min ( 5 % of RTT, 1 ms) If subsequent SACKs need to be sent while the timer has not yet expired, we simply increment tp->compressed_ack. When timer expires, a SACK is sent with the latest information. Whenever an ACK is sent (if data is sent, or if in-order data is received) timer is canceled. Note that tcp_sack_new_ofo_skb() is able to force a SACK to be sent if the sack blocks need to be shuffled, even if the timer has not expired. A new SNMP counter is added in the following patch. Two other patches add sysctls to allow changing the 1,000,000 and 44 values that this commit hard-coded. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: switch pacing timer to softirq based hrtimerEric Dumazet2018-05-111-1/+1
| | | | | | | | | | | | | | linux-4.16 got support for softirq based hrtimers. TCP can switch its pacing hrtimer to this variant, since this avoids going through a tasklet and some atomic operations. pacing timer logic looks like other (jiffies based) tcp timers. v2: use hrtimer_try_to_cancel() in tcp_clear_xmit_timers() to correctly release reference on socket if needed. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: purge write queue upon aborting the connectionSoheil Hassas Yeganeh2018-03-071-0/+1
| | | | | | | | | | | | | | | | | | When the connection is aborted, there is no point in keeping the packets on the write queue until the connection is closed. Similar to a27fd7a8ed38 ('tcp: purge write queue upon RST'), this is essential for a correct MSG_ZEROCOPY implementation, because userspace cannot call close(fd) before receiving zerocopy signals even when the connection is aborted. Fixes: f214f915e7db ("tcp: enable MSG_ZEROCOPY") Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2018-01-291-0/+15
|\ | | | | | | Signed-off-by: David S. Miller <davem@davemloft.net>
| * net: tcp: close sock if net namespace is exitingDan Streetman2018-01-251-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a tcp socket is closed, if it detects that its net namespace is exiting, close immediately and do not wait for FIN sequence. For normal sockets, a reference is taken to their net namespace, so it will never exit while the socket is open. However, kernel sockets do not take a reference to their net namespace, so it may begin exiting while the kernel socket is still open. In this case if the kernel socket is a tcp socket, it will stay open trying to complete its close sequence. The sock's dst(s) hold a reference to their interface, which are all transferred to the namespace's loopback interface when the real interfaces are taken down. When the namespace tries to take down its loopback interface, it hangs waiting for all references to the loopback interface to release, which results in messages like: unregister_netdevice: waiting for lo to become free. Usage count = 1 These messages continue until the socket finally times out and closes. Since the net namespace cleanup holds the net_mutex while calling its registered pernet callbacks, any new net namespace initialization is blocked until the current net namespace finishes exiting. After this change, the tcp socket notices the exiting net namespace, and closes immediately, releasing its dst(s) and their reference to the loopback interface, which lets the net namespace continue exiting. Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1711407 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=97811 Signed-off-by: Dan Streetman <ddstreet@canonical.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | bpf: Add sock_ops RTO callbackLawrence Brakmo2018-01-251-0/+7
| | | | | | | | | | | | | | | | | | | | Adds an optional call to sock_ops BPF program based on whether the BPF_SOCK_OPS_RTO_CB_FLAG is set in bpf_sock_ops_flags. The BPF program is passed 2 arguments: icsk_retransmits and whether the RTO has expired. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2017-12-161-0/+2
|\| | | | | | | | | | | | | Three sets of overlapping changes, two in the packet scheduler and one in the meson-gxl PHY driver. Signed-off-by: David S. Miller <davem@davemloft.net>
| * tcp: refresh tcp_mstamp from timers callbacksEric Dumazet2017-12-131-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Only the retransmit timer currently refreshes tcp_mstamp We should do the same for delayed acks and keepalives. Even if RFC 7323 does not request it, this is consistent to what linux did in the past, when TS values were based on jiffies. Fixes: 385e20706fac ("tcp: use tp->tcp_mstamp in output path") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Mike Maloney <maloney@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Mike Maloney <maloney@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: pause Fast Open globally after third consecutive timeoutYuchung Cheng2017-12-131-16/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | Prior to this patch, active Fast Open is paused on a specific destination IP address if the previous connections to the IP address have experienced recurring timeouts . But recent experiments by Microsoft (https://goo.gl/cykmn7) and Mozilla browsers indicate the isssue is often caused by broken middle-boxes sitting close to the client. Therefore it is much better user experience if Fast Open is disabled out-right globally to avoid experiencing further timeouts on connections toward other destinations. This patch changes the destination-IP disablement to global disablement if a connection experiencing recurring timeouts or aborts due to timeout. Repeated incidents would still exponentially increase the pause time, starting from an hour. This is extremely conservative but an unfortunate compromise to minimize bad experience due to broken middle-boxes. Reported-by: Dragana Damjanovic <ddamjanovic@mozilla.com> Reported-by: Patrick McManus <mcmanus@ducksong.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Wei Wang <weiwan@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: tcp_mtu_probing() cleanupEric Dumazet2017-11-051-17/+14
| | | | | | | | | Reduce one indentation level to make code more readable. tcp_sync_mss() can be factorized. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Namespace-ify sysctl_tcp_thin_linear_timeoutsEric Dumazet2017-10-271-3/+1
| | | | | | | Note that sysctl_tcp_thin_dupack was not used, I deleted it. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* inet/connection_sock: Convert timers to use timer_setup()Kees Cook2017-10-181-7/+11
| | | | | | | | | | | | | | | In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Cc: "David S. Miller" <davem@davemloft.net> Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> Cc: netdev@vger.kernel.org Cc: dccp@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: implement rb-tree based retransmit queueEric Dumazet2017-10-071-9/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Using a linear list to store all skbs in write queue has been okay for quite a while : O(N) is not too bad when N < 500. Things get messy when N is the order of 100,000 : Modern TCP stacks want 10Gbit+ of throughput even with 200 ms RTT flows. 40 ns per cache line miss means a full scan can use 4 ms, blowing away CPU caches. SACK processing often can use various hints to avoid parsing whole retransmit queue. But with high packet losses and/or high reordering, hints no longer work. Sender has to process thousands of unfriendly SACK, accumulating a huge socket backlog, burning a cpu and massively dropping packets. Using an rb-tree for retransmit queue has been avoided for years because it added complexity and overhead, but now is the time to be more resistant and say no to quadratic behavior. 1) RTX queue is no longer part of the write queue : already sent skbs are stored in one rb-tree. 2) Since reaching the head of write queue no longer needs sk->sk_send_head, we added an union of sk_send_head and tcp_rtx_queue Tested: On receiver : netem on ingress : delay 150ms 200us loss 1 GRO disabled to force stress and SACK storms. for f in `seq 1 10` do ./netperf -H lpaa6 -l30 -- -K bbr -o THROUGHPUT|tail -1 done | awk '{print $0} {sum += $0} END {printf "%7u\n",sum}' Before patch : 323.87 351.48 339.59 338.62 306.72 204.07 304.93 291.88 202.47 176.88 2840 After patch: 1700.83 2207.98 2070.17 1544.26 2114.76 2124.89 1693.14 1080.91 2216.82 1299.94 18053 Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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