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path: root/net/ipv4/tcp_output.c
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2017-07-29tcp: avoid bogus gcc-7 array-bounds warningArnd Bergmann
When using CONFIG_UBSAN_SANITIZE_ALL, the TCP code produces a false-positive warning: net/ipv4/tcp_output.c: In function 'tcp_connect': net/ipv4/tcp_output.c:2207:40: error: array subscript is below array bounds [-Werror=array-bounds] tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start; ^~ net/ipv4/tcp_output.c:2207:40: error: array subscript is below array bounds [-Werror=array-bounds] tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~ I have opened a gcc bug for this, but distros have already shipped compilers with this problem, and it's not clear yet whether there is a way for gcc to avoid the warning. As the problem is related to the bitfield access, this introduces a temporary variable to store the old enum value. I did not notice this warning earlier, since UBSAN is disabled when building with COMPILE_TEST, and that was always turned on in both allmodconfig and randconfig tests. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601 Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-04net: reflect mark on tcp syn ack packetsJamal Hadi Salim
SYN-ACK responses on a server in response to a SYN from a client did not get the injected skb mark that was tagged on the SYN packet. Fixes: 84f39b08d786 ("net: support marking accepting TCP sockets") Reviewed-by: Lorenzo Colitti <lorenzo@google.com> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01bpf: Add support for changing congestion controlLawrence Brakmo
Added support for changing congestion control for SOCK_OPS bpf programs through the setsockopt bpf helper function. It also adds a new SOCK_OPS op, BPF_SOCK_OPS_NEEDS_ECN, that is needed for congestion controls, like dctcp, that need to enable ECN in the SYN packets. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01bpf: Add TCP connection BPF callbacksLawrence Brakmo
Added callbacks to BPF SOCK_OPS type program before an active connection is intialized and after a passive or active connection is established. The following patch demostrates how they can be used to set send and receive buffer sizes. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01bpf: Support for setting initial receive windowLawrence Brakmo
This patch adds suppport for setting the initial advertized window from within a BPF_SOCK_OPS program. This can be used to support larger initial cwnd values in environments where it is known to be safe. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01bpf: Support for per connection SYN/SYN-ACK RTOsLawrence Brakmo
This patch adds support for setting a per connection SYN and SYN_ACK RTOs from within a BPF_SOCK_OPS program. For example, to set small RTOs when it is known both hosts are within a datacenter. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01net: convert sock.sk_wmem_alloc from atomic_t to refcount_tReshetova, Elena
refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: David Windsor <dwindsor@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-08tcp: Namespaceify sysctl_tcp_timestampsEric Dumazet
Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-08tcp: Namespaceify sysctl_tcp_window_scalingEric Dumazet
Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-08tcp: Namespaceify sysctl_tcp_sackEric Dumazet
Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-02tcp: remove unnecessary skb_reset_tail_pointer()Eric Dumazet
__pskb_trim_head() does not need to reset skb tail pointer. Also change the comments, __pskb_pull_head() does not exist. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-17tcp: switch TCP TS option (RFC 7323) to 1ms clockEric Dumazet
TCP Timestamps option is defined in RFC 7323 Traditionally on linux, it has been tied to the internal 'jiffies' variable, because it had been a cheap and good enough generator. For TCP flows on the Internet, 1 ms resolution would be much better than 4ms or 10ms (HZ=250 or HZ=100 respectively) For TCP flows in the DC, Google has used usec resolution for more than two years with great success [1] Receive size autotuning (DRS) is indeed more precise and converges faster to optimal window size. This patch converts tp->tcp_mstamp to a plain u64 value storing a 1 usec TCP clock. This choice will allow us to upstream the 1 usec TS option as discussed in IETF 97. [1] https://www.ietf.org/proceedings/97/slides/slides-97-tcpm-tcp-options-for-low-latency-00.pdf 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>
2017-05-17tcp: replace misc tcp_time_stamp to tcp_jiffies32Eric Dumazet
After this patch, all uses of tcp_time_stamp will require a change when we introduce 1 ms and/or 1 us TCP TS option. 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>
2017-05-17tcp: uses jiffies_32 to feed tp->chrono_startEric Dumazet
tcp_time_stamp will no longer be tied to jiffies. 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>
2017-05-17tcp: use tcp_jiffies32 to feed probe_timestampEric Dumazet
Use tcp_jiffies32 instead of tcp_time_stamp, since tcp_time_stamp will soon be only used for TCP TS option. 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>
2017-05-17tcp: use tcp_jiffies32 for rcv_tstamp and lrcvtimeEric Dumazet
Use tcp_jiffies32 instead of tcp_time_stamp, since tcp_time_stamp will soon be only used for TCP TS option. 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>
2017-05-17tcp: use tcp_jiffies32 to feed tp->snd_cwnd_stampEric Dumazet
Use tcp_jiffies32 instead of tcp_time_stamp to feed tp->snd_cwnd_stamp. tcp_time_stamp will soon be a litle bit more expensive than simply reading 'jiffies'. 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>
2017-05-17tcp: use tcp_jiffies32 to feed tp->lsndtimeEric Dumazet
Use tcp_jiffies32 instead of tcp_time_stamp to feed tp->lsndtime. tcp_time_stamp will soon be a litle bit more expensive than simply reading 'jiffies'. 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>
2017-05-17tcp: use tp->tcp_mstamp in output pathEric Dumazet
Idea is to later convert tp->tcp_mstamp to a full u64 counter using usec resolution, so that we can later have fine grained TCP TS clock (RFC 7323), regardless of HZ value. We try to refresh tp->tcp_mstamp only when necessary. 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>
2017-05-16tcp: internal implementation for pacingEric Dumazet
BBR congestion control depends on pacing, and pacing is currently handled by sch_fq packet scheduler for performance reasons, and also because implemening pacing with FQ was convenient to truly avoid bursts. However there are many cases where this packet scheduler constraint is not practical. - Many linux hosts are not focusing on handling thousands of TCP flows in the most efficient way. - Some routers use fq_codel or other AQM, but still would like to use BBR for the few TCP flows they initiate/terminate. This patch implements an automatic fallback to internal pacing. Pacing is requested either by BBR or use of SO_MAX_PACING_RATE option. If sch_fq happens to be in the egress path, pacing is delegated to the qdisc, otherwise pacing is done by TCP itself. One advantage of pacing from TCP stack is to get more precise rtt estimations, and less work done from TX completion, since TCP Small queue limits are not generally hit. Setups with single TX queue but many cpus might even benefit from this. Note that unlike sch_fq, we do not take into account header sizes. Taking care of these headers would add additional complexity for no practical differences in behavior. Some performance numbers using 800 TCP_STREAM flows rate limited to ~48 Mbit per second on 40Gbit NIC. If MQ+pfifo_fast is used on the NIC : $ sar -n DEV 1 5 | grep eth 14:48:44 eth0 725743.00 2932134.00 46776.76 4335184.68 0.00 0.00 1.00 14:48:45 eth0 725349.00 2932112.00 46751.86 4335158.90 0.00 0.00 0.00 14:48:46 eth0 725101.00 2931153.00 46735.07 4333748.63 0.00 0.00 0.00 14:48:47 eth0 725099.00 2931161.00 46735.11 4333760.44 0.00 0.00 1.00 14:48:48 eth0 725160.00 2931731.00 46738.88 4334606.07 0.00 0.00 0.00 Average: eth0 725290.40 2931658.20 46747.54 4334491.74 0.00 0.00 0.40 $ vmstat 1 5 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 4 0 0 259825920 45644 2708324 0 0 21 2 247 98 0 0 100 0 0 4 0 0 259823744 45644 2708356 0 0 0 0 2400825 159843 0 19 81 0 0 0 0 0 259824208 45644 2708072 0 0 0 0 2407351 159929 0 19 81 0 0 1 0 0 259824592 45644 2708128 0 0 0 0 2405183 160386 0 19 80 0 0 1 0 0 259824272 45644 2707868 0 0 0 32 2396361 158037 0 19 81 0 0 Now use MQ+FQ : lpaa23:~# echo fq >/proc/sys/net/core/default_qdisc lpaa23:~# tc qdisc replace dev eth0 root mq $ sar -n DEV 1 5 | grep eth 14:49:57 eth0 678614.00 2727930.00 43739.13 4033279.14 0.00 0.00 0.00 14:49:58 eth0 677620.00 2723971.00 43674.69 4027429.62 0.00 0.00 1.00 14:49:59 eth0 676396.00 2719050.00 43596.83 4020125.02 0.00 0.00 0.00 14:50:00 eth0 675197.00 2714173.00 43518.62 4012938.90 0.00 0.00 1.00 14:50:01 eth0 676388.00 2719063.00 43595.47 4020171.64 0.00 0.00 0.00 Average: eth0 676843.00 2720837.40 43624.95 4022788.86 0.00 0.00 0.40 $ vmstat 1 5 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 2 0 0 259832240 46008 2710912 0 0 21 2 223 192 0 1 99 0 0 1 0 0 259832896 46008 2710744 0 0 0 0 1702206 198078 0 17 82 0 0 0 0 0 259830272 46008 2710596 0 0 0 0 1696340 197756 1 17 83 0 0 4 0 0 259829168 46024 2710584 0 0 16 0 1688472 197158 1 17 82 0 0 3 0 0 259830224 46024 2710408 0 0 0 0 1692450 197212 0 18 82 0 0 As expected, number of interrupts per second is very different. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Van Jacobson <vanj@google.com> Cc: Jerry Chu <hkchu@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-08tcp: make congestion control optionally skip slow start after idleWei Wang
Congestion control modules that want full control over congestion control behavior do not want the cwnd modifications controlled by the sysctl_tcp_slow_start_after_idle code path. So skip those code paths for CC modules that use the cong_control() API. As an example, those cwnd effects are not desired for the BBR congestion control algorithm. Fixes: c0402760f565 ("tcp: new CC hook to set sending rate with rate_sample in any CA state") Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-02Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-nextLinus Torvalds
Pull networking updates from David Millar: "Here are some highlights from the 2065 networking commits that happened this development cycle: 1) XDP support for IXGBE (John Fastabend) and thunderx (Sunil Kowuri) 2) Add a generic XDP driver, so that anyone can test XDP even if they lack a networking device whose driver has explicit XDP support (me). 3) Sparc64 now has an eBPF JIT too (me) 4) Add a BPF program testing framework via BPF_PROG_TEST_RUN (Alexei Starovoitov) 5) Make netfitler network namespace teardown less expensive (Florian Westphal) 6) Add symmetric hashing support to nft_hash (Laura Garcia Liebana) 7) Implement NAPI and GRO in netvsc driver (Stephen Hemminger) 8) Support TC flower offload statistics in mlxsw (Arkadi Sharshevsky) 9) Multiqueue support in stmmac driver (Joao Pinto) 10) Remove TCP timewait recycling, it never really could possibly work well in the real world and timestamp randomization really zaps any hint of usability this feature had (Soheil Hassas Yeganeh) 11) Support level3 vs level4 ECMP route hashing in ipv4 (Nikolay Aleksandrov) 12) Add socket busy poll support to epoll (Sridhar Samudrala) 13) Netlink extended ACK support (Johannes Berg, Pablo Neira Ayuso, and several others) 14) IPSEC hw offload infrastructure (Steffen Klassert)" * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (2065 commits) tipc: refactor function tipc_sk_recv_stream() tipc: refactor function tipc_sk_recvmsg() net: thunderx: Optimize page recycling for XDP net: thunderx: Support for XDP header adjustment net: thunderx: Add support for XDP_TX net: thunderx: Add support for XDP_DROP net: thunderx: Add basic XDP support net: thunderx: Cleanup receive buffer allocation net: thunderx: Optimize CQE_TX handling net: thunderx: Optimize RBDR descriptor handling net: thunderx: Support for page recycling ipx: call ipxitf_put() in ioctl error path net: sched: add helpers to handle extended actions qed*: Fix issues in the ptp filter config implementation. qede: Fix concurrency issue in PTP Tx path processing. stmmac: Add support for SIMATIC IOT2000 platform net: hns: fix ethtool_get_strings overflow in hns driver tcp: fix wraparound issue in tcp_lp bpf, arm64: fix jit branch offset related to ldimm64 bpf, arm64: implement jiting of BPF_XADD ...
2017-04-28tcp: do not underestimate skb->truesize in tcp_trim_head()Eric Dumazet
Andrey found a way to trigger the WARN_ON_ONCE(delta < len) in skb_try_coalesce() using syzkaller and a filter attached to a TCP socket over loopback interface. I believe one issue with looped skbs is that tcp_trim_head() can end up producing skb with under estimated truesize. It hardly matters for normal conditions, since packets sent over loopback are never truncated. Bytes trimmed from skb->head should not change skb truesize, since skb->head is not reallocated. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Andrey Konovalov <andreyknvl@google.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-15Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller
Conflicts were simply overlapping changes. In the net/ipv4/route.c case the code had simply moved around a little bit and the same fix was made in both 'net' and 'net-next'. In the net/sched/sch_generic.c case a fix in 'net' happened at the same time that a new argument was added to qdisc_hash_add(). Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-08net: tcp: Increase TCP_MIB_OUTRSTS even though fail to alloc skbGao Feng
Because TCP_MIB_OUTRSTS is an important count, so always increase it whatever send it successfully or not. Now move the increment of TCP_MIB_OUTRSTS to the top of tcp_send_active_reset to make sure it is increased always even though fail to alloc skb. Signed-off-by: Gao Feng <fgao@ikuai8.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-05net: tcp: Define the TCP_MAX_WSCALE instead of literal number 14Gao Feng
Define one new macro TCP_MAX_WSCALE instead of literal number '14', and use U16_MAX instead of 65535 as the max value of TCP window. There is another minor change, use rounddown(space, mss) instead of (space / mss) * mss; Signed-off-by: Gao Feng <fgao@ikuai8.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-30net: tcp: Refine the __tcp_select_windowGao Feng
1. Move the "window = tp->rcv_wnd;" into the condition block without tp->rx_opt.rcv_wscale. Because it is unnecessary when enable wscale; 2. Use the macro ALIGN instead of two statements. The two statements are used to make window align to 1<<wscale. Use the ALIGN is more clearer. 3. Use the rounddown to make codes clearer. Signed-off-by: Gao Feng <fgao@ikuai8.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-17tcp: accommodate sequence number to a peer's shrunk receive window caused by ↵Cui, Cheng
precision loss in window scaling Prevent sending out a left-shifted sequence number from a Linux sender in response to a peer's shrunk receive-window caused by losing least significant bits in window-scaling. Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Cc: James Morris <jmorris@namei.org> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> Cc: Patrick McHardy <kaber@trash.net> Signed-off-by: Cheng Cui <Cheng.Cui@netapp.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-07tcp: replace dst_confirm with sk_dst_confirmJulian Anastasov
When same struct dst_entry can be used for many different neighbours we can not use it for pending confirmations. Use the new sk_dst_confirm() helper to propagate the indication from received packets to sock_confirm_neigh(). Reported-by: YueHaibing <yuehaibing@huawei.com> Fixes: 5110effee8fd ("net: Do delayed neigh confirmation.") Fixes: f2bb4bedf35d ("ipv4: Cache output routes in fib_info nexthops.") Tested-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Julian Anastasov <ja@ssi.bg> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-03tcp: clear pfmemalloc on outgoing skbEric Dumazet
Josef Bacik diagnosed following problem : I was seeing random disconnects while testing NBD over loopback. This turned out to be because NBD sets pfmemalloc on it's socket, however the receiving side is a user space application so does not have pfmemalloc set on its socket. This means that sk_filter_trim_cap will simply drop this packet, under the assumption that the other side will simply retransmit. Well we do retransmit, and then the packet is just dropped again for the same reason. It seems the better way to address this problem is to clear pfmemalloc in the TCP transmit path. pfmemalloc strict control really makes sense on the receive path. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-03tcp: add tcp_mss_clamp() helperEric Dumazet
Small cleanup factorizing code doing the TCP_MAXSEG clamping. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-02Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller
All merge conflicts were simple overlapping changes. Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-01tcp: fix 0 divide in __tcp_select_window()Eric Dumazet
syszkaller fuzzer was able to trigger a divide by zero, when TCP window scaling is not enabled. SO_RCVBUF can be used not only to increase sk_rcvbuf, also to decrease it below current receive buffers utilization. If mss is negative or 0, just return a zero TCP window. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-29tcp: include locally failed retries in retransmission statsYuchung Cheng
Currently the retransmission stats are not incremented if the retransmit fails locally. But we always increment the other packet counters that track total packet/bytes sent. Awkwardly while we don't count these failed retransmits in RETRANSSEGS, we do count them in FAILEDRETRANS. If the qdisc is dropping many packets this could under-estimate TCP retransmission rate substantially from both SNMP or per-socket TCP_INFO stats. This patch changes this by always incrementing retransmission stats on retransmission attempts and failures. Another motivation is to properly track retransmists in SCM_TIMESTAMPING_OPT_STATS. Since SCM_TSTAMP_SCHED collection is triggered in tcp_transmit_skb(), If tp->total_retrans is incremented after the function, we'll always mis-count by the amount of the latest retransmission. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-25net/tcp-fastopen: refactor cookie check logicWei Wang
Refactor the cookie check logic in tcp_send_syn_data() into a function. This function will be called else where in later changes. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-13tcp: remove early retransmitYuchung Cheng
This patch removes the support of RFC5827 early retransmit (i.e., fast recovery on small inflight with <3 dupacks) because it is subsumed by the new RACK loss detection. More specifically when RACK receives DUPACKs, it'll arm a reordering timer to start fast recovery after a quarter of (min)RTT, hence it covers the early retransmit except RACK does not limit itself to specific inflight or dupack numbers. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-13tcp: remove forward retransmit featureYuchung Cheng
Forward retransmit is an esoteric feature in RFC3517 (condition(3) in the NextSeg()). Basically if a packet is not considered lost by the current criteria (# of dupacks etc), but the congestion window has room for more packets, then retransmit this packet. However it actually conflicts with the rest of recovery design. For example, when reordering is detected we want to be conservative in retransmitting packets but forward-retransmit feature would break that to force more retransmission. Also the implementation is fairly complicated inside the retransmission logic inducing extra iterations in the write queue. With RACK losses are being detected timely and this heuristic is no longer necessary. There this patch removes the feature. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-13tcp: add reordering timer in RACK loss detectionYuchung Cheng
This patch makes RACK install a reordering timer when it suspects some packets might be lost, but wants to delay the decision a little bit to accomodate reordering. It does not create a new timer but instead repurposes the existing RTO timer, because both are meant to retransmit packets. Specifically it arms a timer ICSK_TIME_REO_TIMEOUT when the RACK timing check fails. The wait time is set to RACK.RTT + RACK.reo_wnd - (NOW - Packet.xmit_time) + fudge This translates to expecting a packet (Packet) should take (RACK.RTT + RACK.reo_wnd + fudge) to deliver after it was sent. When there are multiple packets that need a timer, we use one timer with the maximum timeout. Therefore the timer conservatively uses the maximum window to expire N packets by one timeout, instead of N timeouts to expire N packets sent at different times. The fudge factor is 2 jiffies to ensure when the timer fires, all the suspected packets would exceed the deadline and be marked lost by tcp_rack_detect_loss(). It has to be at least 1 jiffy because the clock may tick between calling icsk_reset_xmit_timer(timeout) and actually hang the timer. The next jiffy is to lower-bound the timeout to 2 jiffies when reo_wnd is < 1ms. When the reordering timer fires (tcp_rack_reo_timeout): If we aren't in Recovery we'll enter fast recovery and force fast retransmit. This is very similar to the early retransmit (RFC5827) except RACK is not constrained to only enter recovery for small outstanding flights. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-25ktime: Get rid of the unionThomas Gleixner
ktime is a union because the initial implementation stored the time in scalar nanoseconds on 64 bit machine and in a endianess optimized timespec variant for 32bit machines. The Y2038 cleanup removed the timespec variant and switched everything to scalar nanoseconds. The union remained, but become completely pointless. Get rid of the union and just keep ktime_t as simple typedef of type s64. The conversion was done with coccinelle and some manual mopping up. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
2016-12-21tcp: add a missing barrier in tcp_tasklet_func()Eric Dumazet
Madalin reported crashes happening in tcp_tasklet_func() on powerpc64 Before TSQ_QUEUED bit is cleared, we must ensure the changes done by list_del(&tp->tsq_node); are committed to memory, otherwise corruption might happen, as an other cpu could catch TSQ_QUEUED clearance too soon. We can notice that old kernels were immune to this bug, because TSQ_QUEUED was cleared after a bh_lock_sock(sk)/bh_unlock_sock(sk) section, but they could have missed a kick to write additional bytes, when NIC interrupts for a given flow are spread to multiple cpus. Affected TCP flows would need an incoming ACK or RTO timer to add more packets to the pipe. So overall situation should be better now. Fixes: b223feb9de2a ("tcp: tsq: add shortcut in tcp_tasklet_func()") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Madalin Bucur <madalin.bucur@nxp.com> Tested-by: Madalin Bucur <madalin.bucur@nxp.com> Tested-by: Xing Lei <xing.lei@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05tcp: tsq: move tsq_flags close to sk_wmem_allocEric Dumazet
tsq_flags being in the same cache line than sk_wmem_alloc makes a lot of sense. Both fields are changed from tcp_wfree() and more generally by various TSQ related functions. Prior patch made room in struct sock and added sk_tsq_flags, this patch deletes tsq_flags from struct tcp_sock. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05tcp: tcp_mtu_probe() is likely to exit earlyEric Dumazet
Adding a likely() in tcp_mtu_probe() moves its code which used to be inlined in front of tcp_write_xmit() We still have a cache line miss to access icsk->icsk_mtup.enabled, we will probably have to reorganize fields to help data locality. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05tcp: tsq: add a shortcut in tcp_small_queue_check()Eric Dumazet
Always allow the two first skbs in write queue to be sent, regardless of sk_wmem_alloc/sk_pacing_rate values. This helps a lot in situations where TX completions are delayed either because of driver latencies or softirq latencies. Test is done with no cache line misses. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05tcp: tsq: avoid one atomic in tcp_wfree()Eric Dumazet
Under high load, tcp_wfree() has an atomic operation trying to schedule a tasklet over and over. We can schedule it only if our per cpu list was empty. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05tcp: tsq: add shortcut in tcp_tasklet_func()Eric Dumazet
Under high stress, I've seen tcp_tasklet_func() consuming ~700 usec, handling ~150 tcp sockets. By setting TCP_TSQ_DEFERRED in tcp_wfree(), we give a chance for other cpus/threads entering tcp_write_xmit() to grab it, allowing tcp_tasklet_func() to skip sockets that already did an xmit cycle. In the future, we might give to ACK processing an increased budget to reduce even more tcp_tasklet_func() amount of work. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05tcp: tsq: remove one locked operation in tcp_wfree()Eric Dumazet
Instead of atomically clear TSQ_THROTTLED and atomically set TSQ_QUEUED bits, use one cmpxchg() to perform a single locked operation. Since the following patch will also set TCP_TSQ_DEFERRED here, this cmpxchg() will make this addition free. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05tcp: tsq: add tsq_flags / tsq_enumEric Dumazet
This is a cleanup, to ease code review of following patches. Old 'enum tsq_flags' is renamed, and a new enumeration is added with the flags used in cmpxchg() operations as opposed to single bit operations. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02tcp: randomize tcp timestamp offsets for each connectionFlorian Westphal
jiffies based timestamps allow for easy inference of number of devices behind NAT translators and also makes tracking of hosts simpler. commit ceaa1fef65a7c2e ("tcp: adding a per-socket timestamp offset") added the main infrastructure that is needed for per-connection ts randomization, in particular writing/reading the on-wire tcp header format takes the offset into account so rest of stack can use normal tcp_time_stamp (jiffies). So only two items are left: - add a tsoffset for request sockets - extend the tcp isn generator to also return another 32bit number in addition to the ISN. Re-use of ISN generator also means timestamps are still monotonically increasing for same connection quadruple, i.e. PAWS will still work. Includes fixes from Eric Dumazet. Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30tcp: instrument how long TCP is limited by insufficient send bufferFrancis Yan
This patch measures the amount of time when TCP runs out of new data to send to the network due to insufficient send buffer, while TCP is still busy delivering (i.e. write queue is not empty). The goal is to indicate either the send buffer autotuning or user SO_SNDBUF setting has resulted network under-utilization. The measurement starts conservatively by checking various conditions to minimize false claims (i.e. under-estimation is more likely). The measurement stops when the SOCK_NOSPACE flag is cleared. But it does not account the time elapsed till the next application write. Also the measurement only starts if the sender is still busy sending data, s.t. the limit accounted is part of the total busy time. Signed-off-by: Francis Yan <francisyyan@gmail.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30tcp: instrument how long TCP is limited by receive windowFrancis Yan
This patch measures the total time when the TCP stops sending because the receiver's advertised window is not large enough. Note that once the limit is lifted we are likely in the busy status if we have data pending. Signed-off-by: Francis Yan <francisyyan@gmail.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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