Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756645Ab3GML4g (ORCPT ); Sat, 13 Jul 2013 07:56:36 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:40094 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751100Ab3GML4f (ORCPT ); Sat, 13 Jul 2013 07:56:35 -0400 Date: Sat, 13 Jul 2013 13:56:32 +0200 From: Pavel Machek To: Alan Stern Cc: Yanmin Zhang , shuox.liu@intel.com, linux-kernel@vger.kernel.org, len.brown@intel.com, rjw@sisk.pl, linux-pm@vger.kernel.org Subject: Re: [PATCH] PM: avoid 'autosleep' in shutdown progress Message-ID: <20130713115631.GA16473@amd.pavel.ucw.cz> References: <1373609651.4432.122.camel@ymzhang.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2075 Lines: 45 On Fri 2013-07-12 10:37:33, Alan Stern wrote: > On Fri, 12 Jul 2013, Yanmin Zhang wrote: > > > On Thu, 2013-07-11 at 16:03 +0800, shuox.liu@intel.com wrote: > > > From: Liu ShuoX > > > > > > In shutdown progress, system is possible to do power transition > > > (such as suspend-to-ram) in parallel. It is unreasonable. So, > > > fixes it by adding a system_state checking and queue try_to_suspend > > > again when system status is not running. > > > > > > Signed-off-by: Liu ShuoX > > > --- > > > kernel/power/autosleep.c | 3 ++- > > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > > Without this patch, we hit an hang issue on Android. > > > > Scenario: > > Kernel starts shutdown and calls all device driver's shutdown callback. > > When a driver's shutdown is called, the last wakelock is released and > > suspend-to-ram starts. However, as some driver's shut down callbacks > > already shut down devices and disable runtime pm, the suspend-to-ram > > calls driver's suspend callback without noticing that device is already > > off and causes crash. > > We know the drivers should be fixed, but can we also change generic > > codes a little to make it stronger? > > Indeed, this does seem like the sort of thing we want to have. > Allowing an "automatic" or "opportunistic" sleep in the middle of a > shutdown makes no sense at all. In fact, it might be a good idea to > disable system sleep completely at this time -- not even a write to > /sys/power/state should be allowed to interrupt a shutdown. I'm not completely sure, but as long as userland is running, we should have system_state == RUNNING, no? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/