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[2620:137:e000::1:20]) by mx.google.com with ESMTP id m2-20020a632602000000b005649f303b60si7533138pgm.279.2023.08.08.11.54.33; Tue, 08 Aug 2023 11:54:46 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=ALM6FMLR; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234525AbjHHRXr (ORCPT + 99 others); Tue, 8 Aug 2023 13:23:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45234 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232495AbjHHRXV (ORCPT ); Tue, 8 Aug 2023 13:23:21 -0400 Received: from mail-oa1-x42.google.com (mail-oa1-x42.google.com [IPv6:2001:4860:4864:20::42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 327CB1E5B3; Tue, 8 Aug 2023 09:09:45 -0700 (PDT) Received: by mail-oa1-x42.google.com with SMTP id 586e51a60fabf-1bb89ac2013so4346882fac.1; Tue, 08 Aug 2023 09:09:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1691510958; x=1692115758; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=c3VeUl42GIsBJoy2db7FH5pZ3W66hnMuj1immbzSRdg=; b=ALM6FMLRl3lAWGDKvzWKfwt8peQVQnGhNNub989Bf17M8NiO6I1AzvPjVfvvDd/A9R Cf44N/sNQq6L6iupbwagbLv6jwsROj7mocc/f5rSzUQdoFA2PaF6YKItZKTcMdmF8yrN 6HQoiDS2TbmfI23/uSMkeA4zSe8LiJpyJ06dk63zsu+boRQAttdUzm2gFfvJFooe6SII W70d+8WSUyKmQHvM+QqvL/OrslwiQavSa3fIYpEEdAqH+622792cwFTESOfT+u74GCM9 kemvSs3iHR/mw0m0xLUSRa5xqGhOqIbwZjeTnHfLfXmToaIaDgzA6EkDAzP/4331wyye gM3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691510958; x=1692115758; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=c3VeUl42GIsBJoy2db7FH5pZ3W66hnMuj1immbzSRdg=; b=Mlx1/4AijOUbwOdNzSfR7oh5cIcMwRP6BTxEemvmwNGK7VDc/11zIc9N22NZ0ZApWO 04MjxC5LcByh0ZAa321QKRy2pjrmzYOzhGL0TE/Oj2KBj9BLDnfCfx9ZHPs6JhxyTo2d eSLGPdGUZQ3ySEWxFPREzvYiW/WFPhsCzwknwvPEdkPLOLnLHrzZtZBoML+QUML8OgAE PuYAN61c/n2HXrS6Qt84w8xhaEc+/FN6Id4ic8L32GLgQGxKB0MRjeMvBNaDKdp/21T8 5Exltq6vlQZUFgnuir9mPwXjmdzfQqlu2PS3/LiGgvci8kvhlMDLVzU/my7/ZtzhQTJ3 sivg== X-Gm-Message-State: AOJu0YzQ9xdxT/Kaz9+AO5Of/YYUtC9vfz/hIDG0ZCezV6yAakSHpJyP Mz8XIV5q21UT8wzRhQ6pK2r/ALDNIR7SHzcOZQc= X-Received: by 2002:a05:6a20:3205:b0:12f:382d:2a37 with SMTP id hl5-20020a056a20320500b0012f382d2a37mr12123960pzc.15.1691495951097; Tue, 08 Aug 2023 04:59:11 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.11]) by smtp.gmail.com with ESMTPSA id j22-20020a63e756000000b00563b36264besm6484136pgk.85.2023.08.08.04.59.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Aug 2023 04:59:10 -0700 (PDT) From: menglong8.dong@gmail.com X-Google-Original-From: imagedong@tencent.com To: edumazet@google.com, ncardwell@google.com Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, dsahern@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, flyingpeng@tencent.com, Menglong Dong Subject: [PATCH net-next v3 1/3] net: tcp: send zero-window ACK when no memory Date: Tue, 8 Aug 2023 19:58:33 +0800 Message-Id: <20230808115835.2862058-2-imagedong@tencent.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230808115835.2862058-1-imagedong@tencent.com> References: <20230808115835.2862058-1-imagedong@tencent.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773688205245667859 X-GMAIL-MSGID: 1773688205245667859 From: Menglong Dong For now, skb will be dropped when no memory, which makes client keep retrans util timeout and it's not friendly to the users. In this patch, we reply an ACK with zero-window in this case to update the snd_wnd of the sender to 0. Therefore, the sender won't timeout the connection and will probe the zero-window with the retransmits. Signed-off-by: Menglong Dong --- v3: - refactor the code to avoid code duplication v2: - send 0 rwin ACK for the receive queue empty case when necessary - send the ACK immediately by using the ICSK_ACK_NOW flag --- include/net/inet_connection_sock.h | 3 ++- net/ipv4/tcp_input.c | 18 ++++++++++++------ net/ipv4/tcp_output.c | 14 +++++++++++--- 3 files changed, 25 insertions(+), 10 deletions(-) diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h index c2b15f7e5516..be3c858a2ebb 100644 --- a/include/net/inet_connection_sock.h +++ b/include/net/inet_connection_sock.h @@ -164,7 +164,8 @@ enum inet_csk_ack_state_t { ICSK_ACK_TIMER = 2, ICSK_ACK_PUSHED = 4, ICSK_ACK_PUSHED2 = 8, - ICSK_ACK_NOW = 16 /* Send the next ACK immediately (once) */ + ICSK_ACK_NOW = 16, /* Send the next ACK immediately (once) */ + ICSK_ACK_NOMEM = 32, }; void inet_csk_init_xmit_timers(struct sock *sk, diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 8e96ebe373d7..2ac059483410 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5059,13 +5059,19 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) /* Ok. In sequence. In window. */ queue_and_out: - if (skb_queue_len(&sk->sk_receive_queue) == 0) - sk_forced_mem_schedule(sk, skb->truesize); - else if (tcp_try_rmem_schedule(sk, skb, skb->truesize)) { - reason = SKB_DROP_REASON_PROTO_MEM; - NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP); + if (tcp_try_rmem_schedule(sk, skb, skb->truesize)) { + /* TODO: maybe ratelimit these WIN 0 ACK ? */ + inet_csk(sk)->icsk_ack.pending |= + (ICSK_ACK_NOMEM | ICSK_ACK_NOW); + inet_csk_schedule_ack(sk); sk->sk_data_ready(sk); - goto drop; + + if (skb_queue_len(&sk->sk_receive_queue)) { + reason = SKB_DROP_REASON_PROTO_MEM; + NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP); + goto drop; + } + sk_forced_mem_schedule(sk, skb->truesize); } eaten = tcp_queue_rcv(sk, skb, &fragstolen); diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index c5412ee77fc8..769a558159ee 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -257,11 +257,19 @@ EXPORT_SYMBOL(tcp_select_initial_window); static u16 tcp_select_window(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); - u32 old_win = tp->rcv_wnd; - u32 cur_win = tcp_receive_window(tp); - u32 new_win = __tcp_select_window(sk); struct net *net = sock_net(sk); + u32 old_win = tp->rcv_wnd; + u32 cur_win, new_win; + + /* Make the window 0 if we failed to queue the data because we + * are out of memory. The window is temporary, so we don't store + * it on the socket. + */ + if (unlikely(inet_csk(sk)->icsk_ack.pending & ICSK_ACK_NOMEM)) + return 0; + cur_win = tcp_receive_window(tp); + new_win = __tcp_select_window(sk); if (new_win < cur_win) { /* Danger Will Robinson! * Don't update rcv_wup/rcv_wnd here or else From patchwork Tue Aug 8 11:58:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Menglong Dong X-Patchwork-Id: 132714 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:c44e:0:b0:3f2:4152:657d with SMTP id w14csp2325908vqr; Tue, 8 Aug 2023 11:49:40 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEVyKMhAJmlXdqjtrS9WfwpBjTdRz3zInWLV+nCnp7Mrm1lORnT0dtYPQ8BufYJzeEsaMMf X-Received: by 2002:a05:6a00:14cc:b0:687:1780:aa02 with SMTP id w12-20020a056a0014cc00b006871780aa02mr428888pfu.24.1691520580525; Tue, 08 Aug 2023 11:49:40 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1691520580; cv=none; d=google.com; s=arc-20160816; b=RJ0z1LGMHL58Xq15X8xvwsSMtzkh0BlTTboxJsahd0Wwenp4I3jJ8BmwBz/rjGV6Uw yEEHntUPAL2kIwQ//yU6ifn4amrF7ZAUDja/heiDL7UqD2Za0KMOMaYi9lZBNacg4NFD CxJW6PMUFLeSlk0t0qUtO2ULjNHCt0qkjNgLwt1Uydfnt3ifWCtTZNdAfJrcLjbGiSR6 h0jhZt/55ppnP14K6k7r7iSCZgdwXNVgXljGhOcgOwQ724kkVEmBJDjpO1cSi7PDA+U9 uTqdiu541JnCxhbzP7U4SED4ri5YTBopJpNKb+sCl1RZzdswQu6SFt/eCgJkFfNQYOld 5i7A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=1nhz2+yXHajZnOYlDCo8CCrQ4By4cAhwFG/S6tJ/BEs=; fh=vDYkL/3AO6pdajIq1/coegapVfU0MHkqcFDrLzAYwZQ=; b=zpsaN5yWxNIwETp+5/PuOaL2wsg1FSByhvCLR+6HSlBYBMXwhVI2x3Cvb7mZOtXaAs /rYVCKTTsY0+kPckmqaFstag4FD75GgLK9FYChLIWn76oe4hNUFeDXS3ZTemjsAM/lHd GEtGv9JZMFBBQKcjQRNBIqraHKFJS2VFY/yMzjnmwTk1xcHThhms5nvDIrdWRSYKSDlw MAc/NPHR9PHhIEFMMMCEHFmx0Jbfp1IWhOANp6ndJs1QY9yyTLYl6yXeJiyk7BRDsqrb geCni8jKkasmPCd1CKX35Y+n7L/C9RWEUPiJo7Eu0+jM3AhVlflQnv8TCOBdeRsz6y2S 4xjA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=smgq4l5p; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from out1.vger.email (out1.vger.email. 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This is for the case that the receiver replies an zero-window ACK when it is under memory stress and can't queue the new data. Signed-off-by: Menglong Dong --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 2ac059483410..d34d52fdfdb1 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3525,7 +3525,7 @@ static inline bool tcp_may_update_window(const struct tcp_sock *tp, { return after(ack, tp->snd_una) || after(ack_seq, tp->snd_wl1) || - (ack_seq == tp->snd_wl1 && nwin > tp->snd_wnd); + (ack_seq == tp->snd_wl1 && (nwin > tp->snd_wnd || !nwin)); } /* If we update tp->snd_una, also update tp->bytes_acked */ From patchwork Tue Aug 8 11:58:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Menglong Dong X-Patchwork-Id: 132606 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:c44e:0:b0:3f2:4152:657d with SMTP id w14csp2287200vqr; Tue, 8 Aug 2023 10:42:34 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGa4zJCZIj9+h6GNy4Ynckhft7Di0s6yKmKyY8eZnnlaVLbMPP3ILOinW+DH0aWDUkz6MiQ X-Received: by 2002:a17:902:d509:b0:1b8:9195:1dd8 with SMTP id b9-20020a170902d50900b001b891951dd8mr397416plg.51.1691516554462; Tue, 08 Aug 2023 10:42:34 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1691516554; cv=none; d=google.com; s=arc-20160816; b=wLqwTHSsH1W1kRiWXdFzSK/pWx5BpDVerl21QhS1pJfN9qwdTtA9K8GHPMbMmo4+T6 jvaVt+lahbUX1YiOjbHBrruSxkXtTXGPGTnQeeokHF+sCb0gWLi7G6ZtfCuPaZmvaKJL zzWByik6IiOFFxvepuDhoTw2C5tuzXQFun7b4O7F7aYYtD1LW3jhNnJ0dfAzBW82+nPR V91apQFF8doUvN2d1JShRQRryluxYqaTiFW03o8IUZtNdi45BoqGmbPU6HeCqiftQSbc LMNPTOEr2DxhNQS7+nAmC0eFG9CjZp4DZu+KYAA/ZITM7ABnfylXT0avxCLgp8s5S66y de5g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=KJWy+tJMk/yVxxPHZgp8luxcV72VDkPKoVCNkbs0Mm4=; fh=vDYkL/3AO6pdajIq1/coegapVfU0MHkqcFDrLzAYwZQ=; b=Hrs6nYYifa5elH0VYBSJFmsxr09Bq3uX+bqFVwlR+UEZAp4FVLCf1uhe5b9FxHfboq 2Iv7BmgoU/0PCmsKh//OS8PRPsch/SxL3vpUeopccbbp7jsqW5K2DPU7SjVoqoqShrCd l/y4Az7RPoBREnju4900QmOdHMqupJlBtW4dCXj3bS4c+tozjAHkSYxzwgkiQaFKvn8i GnCYebW52VHk4Ai5zAck7cy4+V/oFEUSV7+Wc2tmRIYmgdX98QY6+PbpiOsyB7tPq5/O 2hvLuPxA7G4m8a+nk33tiMPCunVOWNrYtQdIqO8MfAFRFSC+Lh9t+0ZrHo3YPS65rtMC qZEQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=QqyBIsoG; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from out1.vger.email (out1.vger.email. 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This is not right all the time. The retransmits will become zero-window probes in tcp_retransmit_timer() if the 'snd_wnd==0'. Therefore, the icsk->icsk_rto will come up to TCP_RTO_MAX sooner or later. However, the timer can be delayed and be triggered after 122877ms, not TCP_RTO_MAX, as I tested. Therefore, 'tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX' is always true once the RTO come up to TCP_RTO_MAX, and the socket will die. Fix this by replacing the 'tcp_jiffies32' with '(u32)icsk->icsk_timeout', which is exact the timestamp of the timeout. Meanwhile, using the later one of tp->retrans_stamp and tp->rcv_tstamp as the last updated timestamp in the receiving path, as "tp->rcv_tstamp" can restart from idle, then tp->rcv_tstamp could already be a long time (minutes or hours) in the past even on the first RTO. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Link: https://lore.kernel.org/netdev/CADxym3YyMiO+zMD4zj03YPM3FBi-1LHi6gSD2XT8pyAMM096pg@mail.gmail.com/ Signed-off-by: Menglong Dong --- v3: - use after() instead of max() in tcp_rtx_probe0_timed_out() v2: - consider the case of the connection restart from idle, as Neal comment --- net/ipv4/tcp_timer.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index d45c96c7f5a4..f30d1467771c 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -454,6 +454,18 @@ static void tcp_fastopen_synack_timer(struct sock *sk, struct request_sock *req) req->timeout << req->num_timeout, TCP_RTO_MAX); } +static bool tcp_rtx_probe0_timed_out(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + u32 timeout_ts, rtx_ts, rcv_ts; + + rtx_ts = tp->retrans_stamp; + rcv_ts = tp->rcv_tstamp; + timeout_ts = after(rtx_ts, rcv_ts) ? rtx_ts : rcv_ts; + timeout_ts += TCP_RTO_MAX; + + return after(inet_csk(sk)->icsk_timeout, timeout_ts); +} /** * tcp_retransmit_timer() - The TCP retransmit timeout handler @@ -519,7 +531,7 @@ void tcp_retransmit_timer(struct sock *sk) tp->snd_una, tp->snd_nxt); } #endif - if (tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX) { + if (tcp_rtx_probe0_timed_out(sk)) { tcp_write_err(sk); goto out; }