From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756720Ab0IBTrk (ORCPT ); Thu, 2 Sep 2010 15:47:40 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:43615 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751405Ab0IBTri (ORCPT ); Thu, 2 Sep 2010 15:47:38 -0400 From: "Rafael J. Wysocki" To: Alan Stern Subject: Re: [PATCH] PM: Prevent waiting forever on asynchronous resume after abort Date: Thu, 2 Sep 2010 21:46:03 +0200 User-Agent: KMail/1.13.5 (Linux/2.6.36-rc3-rjw+; KDE/4.4.4; x86_64; ; ) Cc: Colin Cross , linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, Pavel Machek , Len Brown , "Greg Kroah-Hartman" , Randy Dunlap , Andrew Morton References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201009022146.03359.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, September 02, 2010, Alan Stern wrote: > On Wed, 1 Sep 2010, Colin Cross wrote: > > > Only wait on a parent device during resume if the parent device is > > 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. > > This would work okay if C->power.completion had been initialized to the > completed state during boot, right? > > > 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 > > --- > > drivers/base/power/main.c | 3 ++- > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > > index cb784a0..e159910 100644 > > --- a/drivers/base/power/main.c > > +++ b/drivers/base/power/main.c > > @@ -526,7 +526,8 @@ static int device_resume(struct device *dev, pm_message_t state, bool async) > > TRACE_DEVICE(dev); > > TRACE_RESUME(0); > > > > - dpm_wait(dev->parent, async); > > + if (dev->parent && dev->parent->power.status >= DPM_OFF) > > + dpm_wait(dev->parent, async); > > device_lock(dev); > > > > dev->power.status = DPM_RESUMING; > > I think it would be better to change device_pm_init() and add a > complete_all(). I agree. Who's writing the patch? Rafael