From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1CE4ECAAA1 for ; Thu, 27 Oct 2022 11:04:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235202AbiJ0LEh (ORCPT ); Thu, 27 Oct 2022 07:04:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233971AbiJ0LEe (ORCPT ); Thu, 27 Oct 2022 07:04:34 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 511FF5F4D; Thu, 27 Oct 2022 04:04:33 -0700 (PDT) Received: from kwepemi500015.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MyjVT4VnbzHv0F; Thu, 27 Oct 2022 19:04:17 +0800 (CST) Received: from [10.174.178.171] (10.174.178.171) by kwepemi500015.china.huawei.com (7.221.188.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 27 Oct 2022 19:04:30 +0800 Subject: Re: [PATCH net v2] tcp: reset tp->sacked_out when sack is enabled From: "luwei (O)" To: , , , , , , , , CC: , , References: <20221027114930.137735-1-luwei32@huawei.com> Message-ID: Date: Thu, 27 Oct 2022 19:04:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20221027114930.137735-1-luwei32@huawei.com> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.171] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi500015.china.huawei.com (7.221.188.92) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org please ignore this patch£¬ I forgot to change the title ÔÚ 2022/10/27 7:49 PM, Lu Wei дµÀ: > If setsockopt with option name of TCP_REPAIR_OPTIONS and opt_code > of TCPOPT_SACK_PERM is called to enable sack after data is sent > and before data is acked, it will trigger a warning in function > tcp_verify_left_out() as follows: > > ============================================ > WARNING: CPU: 8 PID: 0 at net/ipv4/tcp_input.c:2132 > tcp_timeout_mark_lost+0x154/0x160 > tcp_enter_loss+0x2b/0x290 > tcp_retransmit_timer+0x50b/0x640 > tcp_write_timer_handler+0x1c8/0x340 > tcp_write_timer+0xe5/0x140 > call_timer_fn+0x3a/0x1b0 > __run_timers.part.0+0x1bf/0x2d0 > run_timer_softirq+0x43/0xb0 > __do_softirq+0xfd/0x373 > __irq_exit_rcu+0xf6/0x140 > > This warning occurs in several steps: > Step1. If sack is not enabled, when server receives dup-ack, > it calls tcp_add_reno_sack() to increase tp->sacked_out. > > Step2. Setsockopt() is called to enable sack > > Step3. The retransmit timer expires, it calls tcp_timeout_mark_lost() > to increase tp->lost_out but not clear tp->sacked_out because > sack is enabled and tcp_is_reno() is false. > > So tp->left_out is increased repeatly in Step1 and Step3 and it is > greater than tp->packets_out and trigger the warning. In function > tcp_timeout_mark_lost(), tp->sacked_out will be cleared if Step2 not > happen and the warning will not be triggered. As suggested by Denis > and Eric, TCP_REPAIR_OPTIONS should be prohibited if data was already > sent. > > socket-tcp tests in CRIU has been tested as follows: > $ sudo ./test/zdtm.py run -t zdtm/static/socket-tcp* --keep-going \ > --ignore-taint > > socket-tcp* represent all socket-tcp tests in test/zdtm/static/. > > Fixes: b139ba4e90dc ("tcp: Repair connection-time negotiated parameters") > Signed-off-by: Lu Wei > --- > net/ipv4/tcp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index ef14efa1fb70..ef876e70f7fe 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -3647,7 +3647,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname, > case TCP_REPAIR_OPTIONS: > if (!tp->repair) > err = -EINVAL; > - else if (sk->sk_state == TCP_ESTABLISHED) > + else if (sk->sk_state == TCP_ESTABLISHED && !tp->packets_out) > err = tcp_repair_options_est(sk, optval, optlen); > else > err = -EPERM; -- Best Regards, Lu Wei