From patchwork Thu Jul 27 12:51:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Menglong Dong X-Patchwork-Id: 126966 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:a985:0:b0:3e4:2afc:c1 with SMTP id t5csp1091117vqo; Thu, 27 Jul 2023 06:14:48 -0700 (PDT) X-Google-Smtp-Source: APBJJlH/i5ejAh53NSs/srSkN17mIoYiPwPf2KrpM4GwiaCZugwU/IkRmBbSttEGnvhMY4YN+h1T X-Received: by 2002:a05:6a00:2482:b0:682:e24c:f4e0 with SMTP id c2-20020a056a00248200b00682e24cf4e0mr6998983pfv.11.1690463688089; Thu, 27 Jul 2023 06:14:48 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1690463688; cv=none; d=google.com; s=arc-20160816; b=TAZRLyidF2VHs2ZFFjGOQ3wUAd/A08CpJAb+T2BHD0SHtER12cMJFdjPULhMmtuyKl /Mpxgpmul1trgxkVLAEbqhohJDEtuoEx97n176p+ZoUh0jSGTTp9momH8AQb0XGEV5tR oiXkOkkpgOAfA5kNp9TcH6rghKEPJTLUP0nvofuwHPhD0z4C0/3uLG0Tl07dR4drl3dA jkAf5I+muugvEDGd3jhWw7YVB/7bJAaCq+J1zVQ8dd6UREwu0wOkkRmge/UV0ZaVgkSu cY0qXYeVDd84ccsGmJ+mDuUaxXz5I9eaYnLm5qtaEkyvr5RFCADiRTZfIiTMsFFylT8r 3Qnw== 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=/1M9X9cFhRpVGts4/6dZs2oXMtLocqBd/PjGY4NYMgE=; fh=XTrcsWlG6eWRF8kMD39RggsfnzCcPZgP6zx8G4b7bEM=; b=a1XoRyInuXVhqbVAY8dfVs8dtSMWTzB8QDMLkTV4ca5Fhgqet+0tUdH5VcQi3rMToT wwB/gZOjpjhpmVyLC4ckAN/ETSnu3IYbadoTTC8OE7BHTicYiKos5Ty0PUkEjhRqFMXN +8XjYoFGp93O9rg3SPXHC94wv1BF2p7akcVkPo88VvmjH41Kcy+j243cwXSUoN0/roul 0HSYfMqseIV1EekpJlj/vVpq2OXrfamJXoSCV5vOM7fh7DPW/hJjScqZeZsoeAOr0zMj IK7ftFMm8Aj4iTxUyHiUVzg1RUTe+Y+7zt+xSivHpR54fsc4tqCHDvuZjM07Jw9V3KI8 QllQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=I9eJSV42; 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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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 --- include/net/inet_connection_sock.h | 3 ++- net/ipv4/tcp_input.c | 4 ++-- net/ipv4/tcp_output.c | 14 +++++++++++--- 3 files changed, 15 insertions(+), 6 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 3cd92035e090..03111af6115d 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5061,7 +5061,8 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) reason = SKB_DROP_REASON_PROTO_MEM; NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP); sk->sk_data_ready(sk); - goto drop; + inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOMEM; + goto out_of_window; } eaten = tcp_queue_rcv(sk, skb, &fragstolen); @@ -5102,7 +5103,6 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) out_of_window: tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS); inet_csk_schedule_ack(sk); -drop: tcp_drop_reason(sk, skb, reason); return; } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 2cb39b6dad02..81aa2c615924 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 Thu Jul 27 12:51:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Menglong Dong X-Patchwork-Id: 126967 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:a985:0:b0:3e4:2afc:c1 with SMTP id t5csp1091206vqo; Thu, 27 Jul 2023 06:14:54 -0700 (PDT) X-Google-Smtp-Source: APBJJlGw1ZHxq9ZwLbw/lbvpV0gBn5r/dUl2NSYqX+HTboTblrNHY9GmSZuh2DYXI9QzLxhrOcAy X-Received: by 2002:a05:6808:1b2c:b0:3a4:1f10:c092 with SMTP id bx44-20020a0568081b2c00b003a41f10c092mr3792677oib.32.1690463694330; Thu, 27 Jul 2023 06:14:54 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1690463694; cv=none; d=google.com; s=arc-20160816; b=uWiZ6V0RRmcTye+zYODN/83W2+/Dk45m23vwp2TK5tdpISWJ7HXzcruElGkd7OXhAm PnKR8706fxt7XM796iIu1nNzcfv7q4jUri4RGMOx0R/NFwe/oAoTE2f/MQG2XoYPQ1J9 vCgfPpK/uVFOvb0mpZP2GEt+Kw71j7xjkVTTeAZ1l/FgimQy2yp37+bbB6wX+WVX1mx7 zdbHa/eefqhLSkpG0aaKMvX1nCp2GSKVuTEBFSqt4fgYBOOa2AFILkHRywbNA6gNca22 8OJ1iLKlt9XY9HmVvPKEvo7iJ1VF4452rLJsAZnSWtEfU4+uvgZdPD77hteSeE5NvJhI JuMg== 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=+xv0faR8qn1Zj+OjUn+kfjlxGEdmNSeFnyT9mw1cYmU=; fh=XTrcsWlG6eWRF8kMD39RggsfnzCcPZgP6zx8G4b7bEM=; b=TwVa5/CSL2I/RCSCWWBK8kVg5vsItFNh/+r35u+CCY3bfJzsXKa4UFLs9IFrhcg0si 9ZQyecJsCc+TEF+n5KDJLRdpENE7zoj1PvRdM2/9C6e0jqoYBrmwUXktW5UAbLit04cb nu9uzUabNbYZgOGIUpOUiH50gu56sQux5lkaPPsWCX36bfmsvaNA/knwBCgfiZqTsigk xCKY9ZixAZxaWqVGlVL0i7dtg0BJg7s6DOrwMGUS2DYPiFhnxpsyuIgOdMZ+ywFxSCgX XDixsS/syAOUA6HIdCNVd2B4792D0BLGifDKZyyBrNvwsFgcSbU95LI1Ugr49KOIyzYF suEw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=XxuM3J9v; 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 03111af6115d..d13b89370f76 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3526,7 +3526,7 @@ 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 Thu Jul 27 12:51:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Menglong Dong X-Patchwork-Id: 126968 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:a985:0:b0:3e4:2afc:c1 with SMTP id t5csp1091250vqo; Thu, 27 Jul 2023 06:14:58 -0700 (PDT) X-Google-Smtp-Source: APBJJlFeB+JolYkeV6N9+Kex6K+l5at2xrnfJ7WAeofM9MXTIqgx5x+3JjDdPtLTdK+kXFGQOdo9 X-Received: by 2002:a17:90a:8995:b0:268:37b:a10e with SMTP id v21-20020a17090a899500b00268037ba10emr3889255pjn.11.1690463697862; Thu, 27 Jul 2023 06:14:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1690463697; cv=none; d=google.com; s=arc-20160816; b=ykhUB6pw5smRTZEqHkfO28H9B6UqVzCaBhfQVPnDXyvCs15zowsjL35W1QRY1UJ6Xb MZC5TKi8ZG5EQFvbbXCWa9+YJJEsUNPqXZwPOZPfSjMpuoO/8ktMbCiuewiUJypkSULv 5iJieo6D9sgzMJknipKX8KSc3f74ZHqEMF+LMaq5u+d3z2UIOcyftNoOlsWjpzuhGo/V bHk5oBHQ3w+Iodhp0RHBX7GpGYMDKRWPIyjvndvosWnprIbj5ActoWcYkyuJ9SO3tUNV lU6JrO9yQJMx6bz3dgZdReX0eEyNQBR/MgIk95WEwz6ch6fVSVQM1u6sdsLAF9MsWv0i DaXQ== 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=GQgiv4sJ/sPXZQ43kqJjA4dVyOkNO7+7aA6t8NxmmyQ=; fh=XTrcsWlG6eWRF8kMD39RggsfnzCcPZgP6zx8G4b7bEM=; b=KK5W/eX1o+Aysnlbtu1PuT1I/SbvqtZLD2ogoUAvatjAsyIdYNcZ1kmCCDdn9F4VF7 f7U8UATq978JljTgNC3E6QnVTFqMXPEmg3cEUjcXYJ4/kIlXFYT4OCiVQaZv14zqCsDR VoE9PoPYc2qTSpPF60a9s4h7iB2S4kFJ39MaM8xClWQhqkL5LhxsMKrTjZzDQs2cUjqB wP1sXrAAP8t99Yp1gX5EtQzY4e3Yz7IalSCckspE0aPQ794qOeqPz1l/Np4wbeSaj3KC jj7j0wtodVwwSMEEVdjLs0L5q5Ko5ERAETz+yVaSe/4iBfal21eEmiJXXfyFnqIUsegV BFQw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=eeAxrZ9W; 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 is not precise enough, as it base on timer wheel. Sorry that I am not good at timer, but I know the concept of time-wheel. The longer of the timer, the rougher it will be. So the timeout is not triggered after TCP_RTO_MAX, but 122877ms as I tested. Therefore, 'tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX' is always true once the RTO come up to TCP_RTO_MAX. Fix this by replacing the 'tcp_jiffies32' with '(u32)icsk->icsk_timeout', which is exact the timestamp of the timeout. Signed-off-by: Menglong Dong --- net/ipv4/tcp_timer.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 470f581eedd4..3a20db15a186 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -511,7 +511,11 @@ void tcp_retransmit_timer(struct sock *sk) tp->snd_una, tp->snd_nxt); } #endif - if (tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX) { + /* It's a little rough here, we regard any valid packet that + * update tp->rcv_tstamp as the reply of the retransmitted + * packet. + */ + if ((u32)icsk->icsk_timeout - tp->rcv_tstamp > TCP_RTO_MAX) { tcp_write_err(sk); goto out; }