From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752403AbdJTHtJ (ORCPT ); Fri, 20 Oct 2017 03:49:09 -0400 Received: from mailgw1.fjfi.cvut.cz ([147.32.9.3]:37224 "EHLO mailgw1.fjfi.cvut.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752355AbdJTHtF (ORCPT ); Fri, 20 Oct 2017 03:49:05 -0400 X-CTU-FNSPE-Virus-Scanned: amavisd-new at fjfi.cvut.cz DKIM-Filter: OpenDKIM Filter v2.11.0 mailgw1.fjfi.cvut.cz 856A6A026E Date: Fri, 20 Oct 2017 09:49:00 +0200 (CEST) From: David Kozub To: Daniel Lezcano cc: Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH] clockevents/drivers/cs5535: improve resilience to spurious interrupts In-Reply-To: Message-ID: References: <20171019211651.039346004D@linux.fjfi.cvut.cz> <0ea5f585-5407-8bcb-1cc9-9a2f3f11b78e@linaro.org> User-Agent: Alpine 2.21 (LRH 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Oct 2017, Daniel Lezcano wrote: > 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. I will try to test that. But I won't have access to the device till Sunday evening. I've had big trouble trying to run kernels > 4.1-rc5 on the device and if I'm looking correctly the commit was introduced in 4.3-rc1. But I'll try to figure something out. Best regards, David