Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751791AbdIUTkN (ORCPT ); Thu, 21 Sep 2017 15:40:13 -0400 Received: from mail-pf0-f175.google.com ([209.85.192.175]:47208 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751636AbdIUTkL (ORCPT ); Thu, 21 Sep 2017 15:40:11 -0400 X-Google-Smtp-Source: AOwi7QB7T5PzSfnfqX2r3a9zRAiyssQVEtrL2VxvCRmeOamQh19wimFqKfAGWPjcNjGUukMh+Hfh2g== Subject: Re: [tip:timers/core] kselftests: timers: set-timer-lat: Tweak reporting when timer fires early To: Shuah Khan , Prarit Bhargava , John Stultz , Shuah Khan Cc: lkml , Richard Cochran , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Stephen Boyd , Miroslav Lichvar , linux-tip-commits@vger.kernel.org, Josef Bacik References: <04d5e9e4-ef81-a9e7-8180-2c668e3af9d0@kernel.org> <36087647-31b1-95a1-fd74-b22f7d931010@redhat.com> From: Greg Hackmann Message-ID: Date: Thu, 21 Sep 2017 12:40:08 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3588 Lines: 89 On 09/20/2017 04:38 PM, Shuah Khan wrote: > On 09/20/2017 06:31 AM, Prarit Bhargava wrote: >> On 09/19/2017 11:36 PM, John Stultz wrote: >>> On Tue, Sep 19, 2017 at 6:02 PM, Shuah Khan wrote: >>>> Hi Greg, >>>> >>>> On 08/20/2017 03:56 AM, tip-bot for Greg Hackmann wrote: >>>>> Commit-ID: a524b1184b8e86141d689fa78ad150fbf2db9b4c >>>>> Gitweb: http://git.kernel.org/tip/a524b1184b8e86141d689fa78ad150fbf2db9b4c >>>>> Author: Greg Hackmann >>>>> AuthorDate: Tue, 25 Jul 2017 14:36:25 -0700 >>>>> Committer: John Stultz >>>>> CommitDate: Thu, 17 Aug 2017 12:14:54 -0700 >>>>> >>>>> kselftests: timers: set-timer-lat: Tweak reporting when timer fires early >>>>> >>>>> Rather than printing an error inside the alarm signal handler, set a >>>>> flag that we check later. This keeps the test from spamming the console >>>>> every time the alarm fires early. It also fixes the test exiting with >>>>> error code 0 if this was the only test failure. >>>>> >>>>> Cc: Thomas Gleixner >>>>> Cc: Ingo Molnar >>>>> Cc: Miroslav Lichvar >>>>> Cc: Richard Cochran >>>>> Cc: Prarit Bhargava >>>>> Cc: Stephen Boyd >>>>> Cc: Shuah Khan >>>>> Cc: linux-kselftest@vger.kernel.org >>>>> Signed-off-by: Greg Hackmann >>>>> Signed-off-by: John Stultz >>>> >>>> This commit is making the set-timer-lat hang. I reverted this commit >>>> and there is no hang. Could you please take a look and see if this >>>> commit should be reverted. >>>> >>>> make kselftest as well as make -C tools/testing/selftests/timers run_tests >>>> hang. >>> >>> Do you have any specific details as to how the test hangs? (ie: Log >>> data, as in where it might be when it hangs? Any details about the >>> machine?) >>> >>> I'm not seeing it so far in my testing. >>> >> >> I just ran it here and don't see any issues. I'll try on a few other boxes >> to make sure. >> >> # make -C tools/testing/selftests/timers run_tests > > John/Prarit, > > Thanks for getting back to me. I isolated the problem to redirecting > test output. If I redirect the output it hangs. > > ./set-timer-lat > /tmp/set-timer-lat 2>&1 > > it hangs. The reason I am seeing this is because there is a patch > that came in recently to redirect individual test output to a separate > file to make it easier to understand the test results. > > Looks like Commits 28be3f8f48cfb3cf024860f042d424cd4824f5f7 and/or > a524b1184b8e86141d689fa78ad150fbf2db9b4c add dependency on stdin/out/err > to the test. > > Anyway just an update. It can be reproduced easily. If we have tests > that can't tolerate redirecting output, I might end up dropping the > patch that is in linux-kselftest fixes > > fbcab13d2e2511a858590846ac2e2d7cbd830591 > > So fat set-timer-lat is the only one I found. > > thanks, > -- Shuah > I'm able to reproduce this locally, though I'm not sure it's a redirection issue. 28be3f8f48cf ("kselftests: timers: set-timer-lat: Add one-shot timer test cases") appears to have a regression where if timer_create() fails due to missing CAP_WAKE_ALARM, do_timer() will still try to run the test anyway. Please revert 28be3f8f48cf and verify whether this fixes the problem for you. If so, I'll send a V2 as soon as possible that fixes the issue. (Basically, setup_timer() needs a discrete return value for unsupported test cases.) Sorry for the confusion.