Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757519Ab3GLOhg (ORCPT ); Fri, 12 Jul 2013 10:37:36 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:32951 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757203Ab3GLOhe (ORCPT ); Fri, 12 Jul 2013 10:37:34 -0400 Date: Fri, 12 Jul 2013 10:37:33 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Yanmin Zhang cc: shuox.liu@intel.com, , , , , Subject: Re: [PATCH] PM: avoid 'autosleep' in shutdown progress In-Reply-To: <1373609651.4432.122.camel@ymzhang.sh.intel.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1721 Lines: 40 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. Alan Stern -- 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/