From nobody Wed Apr 8 14:04:12 2026 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 F019EC433FE for ; Wed, 26 Oct 2022 14:12:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234201AbiJZOMt (ORCPT ); Wed, 26 Oct 2022 10:12:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234192AbiJZOMo (ORCPT ); Wed, 26 Oct 2022 10:12:44 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54FB710EE54; Wed, 26 Oct 2022 07:12:43 -0700 (PDT) Received: from kwepemi500015.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4My9cn5CFzzVj66; Wed, 26 Oct 2022 22:07:53 +0800 (CST) Received: from huawei.com (10.175.101.6) 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; Wed, 26 Oct 2022 22:12:40 +0800 From: Lu Wei To: , , , , , , , , Subject: [PATCH net] tcp: reset tp->sacked_out when sack is enabled Date: Wed, 26 Oct 2022 23:15:58 +0800 Message-ID: <20221026151558.4165020-1-luwei32@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) 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 Content-Type: text/plain; charset="utf-8" The meaning of tp->sacked_out depends on whether sack is enabled or not. If setsockopt is called to enable sack_ok via tcp_repair_options_est(), tp->sacked_out should be cleared, or it will trigger warning in tcp_verify_left_out as follows: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D 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. So this patch clears tp->sacked_out in tcp_repair_options_est(). Fixes: b139ba4e90dc ("tcp: Repair connection-time negotiated parameters") Signed-off-by: Lu Wei --- net/ipv4/tcp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index ef14efa1fb70..188d5c0e440f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3282,6 +3282,9 @@ static int tcp_repair_options_est(struct sock *sk, so= ckptr_t optbuf, if (opt.opt_val !=3D 0) return -EINVAL; =20 + if (tcp_is_reno(tp)) + tp->sacked_out =3D 0; + tp->rx_opt.sack_ok |=3D TCP_SACK_SEEN; break; case TCPOPT_TIMESTAMP: --=20 2.31.1