Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964811AbcDYUGO (ORCPT ); Mon, 25 Apr 2016 16:06:14 -0400 Received: from mail-qg0-f68.google.com ([209.85.192.68]:36815 "EHLO mail-qg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933160AbcDYUGM convert rfc822-to-8bit (ORCPT ); Mon, 25 Apr 2016 16:06:12 -0400 MIME-Version: 1.0 In-Reply-To: <20160418123547.GK29406@pali> References: <1457740175-8327-1-git-send-email-gabriele.mzt@gmail.com> <20160328173309.GA26086@dvhart-mobl5.amr.corp.intel.com> <4072492.lANJWhSkYa@vostro.rjw.lan> <20160418123547.GK29406@pali> Date: Mon, 25 Apr 2016 22:06:11 +0200 Message-ID: Subject: Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended From: Gabriele Mazzotta To: =?UTF-8?Q?Pali_Roh=C3=A1r?= Cc: Darren Hart , "D. Jared Dominguez" , "platform-driver-x86@vger.kernel.org" , Alex Hung , Andrei Borzenkov , "linux-kernel@vger.kernel.org" , "Rafael J. Wysocki" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3879 Lines: 90 2016-04-18 14:35 GMT+02:00 Pali Rohár : > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote: >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár : >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár : >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: >> > > >> >> +#ifdef CONFIG_PM_SLEEP >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) >> > > >> >> +{ >> > > >> >> + struct rbtn_data *rbtn_data = context; >> > > >> >> + >> > > >> >> + rbtn_data->suspended = false; >> > > >> >> +} >> > > >> >> + >> > > >> >> +static int rbtn_suspend(struct device *dev) >> > > >> >> +{ >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> > > >> >> + >> > > >> >> + rbtn_data->suspended = true; >> > > >> >> + >> > > >> >> + return 0; >> > > >> >> +} >> > > >> >> + >> > > >> >> +static int rbtn_resume(struct device *dev) >> > > >> >> +{ >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> > > >> >> + acpi_status status; >> > > >> >> + >> > > >> >> + /* >> > > >> >> + * Clear the flag only after we received the extra >> > > >> >> + * ACPI notification. >> > > >> >> + */ >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, >> > > >> >> + rbtn_acpi_clear_flag, rbtn_data); >> > > >> >> + if (ACPI_FAILURE(status)) >> > > >> >> + rbtn_data->suspended = false; >> > > >> > >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, >> > > >> > right? And that will set suspended to false. When acpi_os_execute fails, >> > > >> > then it set suspended too to false... Then whole acpi_os_execute doing >> > > >> > just "barrier" after which suspended flag can be set to false. So I >> > > >> > think rbtn_acpi_clear_flag function is not needed here. >> > > >> > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was >> > > >> > reason to do that flag clearing at "two places"? >> > > >> >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so >> > > >> I can't clear the flag from rbtn_resume. >> > > > >> > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? >> > > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue >> > > for deferred execution. >> > >> > +Rafael for context/advice on the use of acpi_os_execute here. >> > >> > This is true, but a quick scan through that call path doesn't tell me why we >> > would need to call it here instead of just setting rbtn_data->suspended = false. >> > The comment suggests waiting for the event, but is that what this is doing? It >> > appears to me to be immediately scheduling the function to a work queue, not >> > waiting for the event notifier. >> >> I think this is supposed to work as a barrier. That is, it will only run after >> all events in the queue have been processed. >> >> I'm not sure if that's necessary, though. >> >> Thanks, >> Rafael >> > > Darren, Gabriele, what is state of this patch? Bug is not still fixed, > right? Yes, the bug is still there and this patch fixes it. Just to make it clear, we need the barrier. Andrei could reproduce the bug without it [1], but not with it, as he confirmed in this thread [2]. [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937 > -- > Pali Rohár > pali.rohar@gmail.com