From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751857AbdJTGqT (ORCPT ); Fri, 20 Oct 2017 02:46:19 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:50431 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751003AbdJTGqS (ORCPT ); Fri, 20 Oct 2017 02:46:18 -0400 X-Google-Smtp-Source: ABhQp+R6vvLX7nYwwbobqxS/0hmWHSc3fLMMed5WNE/281cbIqZURFHjDBPqnwtMmRdz2xgvIxL5KA== Subject: Re: [PATCH] clockevents/drivers/cs5535: improve resilience to spurious interrupts To: Thomas Gleixner Cc: David Kozub , linux-kernel@vger.kernel.org References: <20171019211651.039346004D@linux.fjfi.cvut.cz> <0ea5f585-5407-8bcb-1cc9-9a2f3f11b78e@linaro.org> From: Daniel Lezcano Message-ID: Date: Fri, 20 Oct 2017 08:46:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/10/2017 00:25, Thomas Gleixner wrote: > On Fri, 20 Oct 2017, Daniel Lezcano wrote: > >> On 19/10/2017 22:57, David Kozub wrote: >>> This solves a BUG on ALIX 2c3 where mfgpt_tick is called before >>> clockevents_config_and_register returns. This caused mfgpt_tick to call a >>> null function pointer. >>> >>> Thanks to Daniel Lezcano and Thomas Gleixner for helping me analyze this >>> and suggesting a solution. >>> >>> Suggested-by: Thomas Gleixner >>> Signed-off-by: David Kozub >>> --- >> >> Thank for sending this fix. >> >> Can you check if the commit 8f9327cbb is the one introducing the >> regression ? So we can add the proper tags and propagate the fix to stable. > > No it's not. > > - if (cs5535_tick_mode == CLOCK_EVT_MODE_SHUTDOWN) > + if (clockevent_state_shutdown(&cs5535_clockevent)) > > This particular problem of the missing detached state check has been there > forever and went unnoticed for whatever reason. The detached condition was artificially caught by the initialized variable: -static unsigned int cs5535_tick_mode = CLOCK_EVT_MODE_SHUTDOWN; The patch 8f9327cbb removes the variable, so very likely this is where the problem appeared. -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog