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 2DAEAEE14AA for ; Thu, 7 Sep 2023 01:01:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230325AbjIGBBi (ORCPT ); Wed, 6 Sep 2023 21:01:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37136 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229563AbjIGBBh (ORCPT ); Wed, 6 Sep 2023 21:01:37 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AE4EE8; Wed, 6 Sep 2023 18:01:33 -0700 (PDT) Received: from dggpeml500012.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Rh19V427qz1M8v6; Thu, 7 Sep 2023 08:59:42 +0800 (CST) Received: from [10.67.110.218] (10.67.110.218) by dggpeml500012.china.huawei.com (7.185.36.15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 7 Sep 2023 09:01:30 +0800 Message-ID: Date: Thu, 7 Sep 2023 09:01:30 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: "[PATCH] selftests/ftrace: Correctly enable event in instance-event.tc" Content-Language: en-US To: Steven Rostedt , Naresh Kamboju CC: , , , , , , , References: <20230906142652.191866-1-naresh.kamboju@linaro.org> <20230906103718.0405ccb4@gandalf.local.home> <20230906173706.7aeb8716@gandalf.local.home> From: Zheng Yejian In-Reply-To: <20230906173706.7aeb8716@gandalf.local.home> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.110.218] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpeml500012.china.huawei.com (7.185.36.15) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On 2023/9/7 05:37, Steven Rostedt wrote: > On Wed, 6 Sep 2023 10:37:18 -0400 > Steven Rostedt wrote: > >>> Log details, >>> ------------- >>> # ok 45 ftrace - test tracing error log support >>> <47>[ 1373.662292] systemd-journald[90]: Sent WATCHDOG=1 notification. >>> # ok 46 Test creation and deletion of trace instances while setting an event >> >> It's definitely a race with the creation and deletion of instances. >> >> I'm going to run it on my laptop VM and see if that reproduces it. My other >> VM is on a pretty powerful machine, and perhaps that's keeping it from >> hitting the race. > > Putting in a while loop of: > > # while :; do ./ftracetest test.d/instances/instance-event.tc ; done > In test.d/instances/instance-event.tc, concurrently create/delete/access intances just about 1 second and then killed them, it may cause missing the race. No longer sleep and kill, following testcase can also reproduce: ``` #!/bin/bash cd /sys/kernel/tracing/instances instance_slam() { while :; do mkdir foo 2> /dev/null rmdir foo 2> /dev/null done } instance_set() { while :; do echo 1 > foo/events/sched/sched_switch/enable done 2> /dev/null } instance_slam & p1=$! echo $p1 instance_set & p2=$! echo $p2 ``` -- Thanks, Zheng Yejian > eventually triggered the bug. Looks like this is really an existing bug not > related to the eventfs, but the eventfs code actually opened up the window > of this race. > > Hopefully I'll have a fix shortly. > > -- Steve >