From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756740Ab0IBX1F (ORCPT ); Thu, 2 Sep 2010 19:27:05 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:44467 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750887Ab0IBX1D (ORCPT ); Thu, 2 Sep 2010 19:27:03 -0400 From: "Rafael J. Wysocki" To: Colin Cross Subject: Re: [PATCH v2] PM: Prevent waiting forever on asynchronous resume after abort Date: Fri, 3 Sep 2010 01:25:28 +0200 User-Agent: KMail/1.13.5 (Linux/2.6.36-rc3-rjw+; KDE/4.4.4; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, Pavel Machek , Len Brown , "Greg Kroah-Hartman" , Alan Stern , Randy Dunlap References: <201009022340.41584.rjw@sisk.pl> <1283468359-6642-1-git-send-email-ccross@android.com> In-Reply-To: <1283468359-6642-1-git-send-email-ccross@android.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-2" Content-Transfer-Encoding: 7bit Message-Id: <201009030125.28494.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday, September 03, 2010, Colin Cross wrote: > During suspend, the power.completion is expected to be set when a > device has not yet started suspending. Set it on init to fix a > corner case where a device is resumed when its parent has never > suspended. > > Consider three drivers, A, B, and C. The parent of A is C, and C > has async_suspend set. On boot, C->power.completion is initialized > to 0. > > During the first suspend: > suspend_devices_and_enter(...) > dpm_resume(...) > device_suspend(A) > device_suspend(B) returns error, aborts suspend > dpm_resume_end(...) > dpm_resume(...) > device_resume(A) > dpm_wait(A->parent == C) > wait_for_completion(C->power.completion) > > The wait_for_completion will never complete, because > complete_all(C->power.completion) will only be called from > device_suspend(C) or device_resume(C), neither of which is called > if suspend is aborted before C. > > After a successful suspend->resume cycle, where B doesn't abort > suspend, C->power.completion is left in the completed state by the > call to device_resume(C), and the same call path will work if B > aborts suspend. > > Signed-off-by: Colin Cross Thanks, rebased on top of the current Linus' tree and applied to suspend-2.6/pm-fixes . Rafael > --- > drivers/base/power/main.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index cb784a0..b1b4029 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -63,6 +63,7 @@ void device_pm_init(struct device *dev) > { > dev->power.status = DPM_ON; > init_completion(&dev->power.completion); > + complete_all(&dev->power.completion); > pm_runtime_init(dev); > } > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH v2] PM: Prevent waiting forever on asynchronous resume after abort Date: Fri, 3 Sep 2010 01:25:28 +0200 Message-ID: <201009030125.28494.rjw@sisk.pl> References: <201009022340.41584.rjw@sisk.pl> <1283468359-6642-1-git-send-email-ccross@android.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1283468359-6642-1-git-send-email-ccross@android.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Colin Cross Cc: Randy Dunlap , Len Brown , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org List-Id: linux-pm@vger.kernel.org On Friday, September 03, 2010, Colin Cross wrote: > During suspend, the power.completion is expected to be set when a > device has not yet started suspending. Set it on init to fix a > corner case where a device is resumed when its parent has never > suspended. > > Consider three drivers, A, B, and C. The parent of A is C, and C > has async_suspend set. On boot, C->power.completion is initialized > to 0. > > During the first suspend: > suspend_devices_and_enter(...) > dpm_resume(...) > device_suspend(A) > device_suspend(B) returns error, aborts suspend > dpm_resume_end(...) > dpm_resume(...) > device_resume(A) > dpm_wait(A->parent == C) > wait_for_completion(C->power.completion) > > The wait_for_completion will never complete, because > complete_all(C->power.completion) will only be called from > device_suspend(C) or device_resume(C), neither of which is called > if suspend is aborted before C. > > After a successful suspend->resume cycle, where B doesn't abort > suspend, C->power.completion is left in the completed state by the > call to device_resume(C), and the same call path will work if B > aborts suspend. > > Signed-off-by: Colin Cross Thanks, rebased on top of the current Linus' tree and applied to suspend-2.6/pm-fixes . Rafael > --- > drivers/base/power/main.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index cb784a0..b1b4029 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -63,6 +63,7 @@ void device_pm_init(struct device *dev) > { > dev->power.status = DPM_ON; > init_completion(&dev->power.completion); > + complete_all(&dev->power.completion); > pm_runtime_init(dev); > } > >