From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754538AbcKAESb (ORCPT ); Tue, 1 Nov 2016 00:18:31 -0400 Received: from cloudserver094114.home.net.pl ([79.96.170.134]:46356 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752538AbcKAES3 (ORCPT ); Tue, 1 Nov 2016 00:18:29 -0400 From: "Rafael J. Wysocki" To: Brian Norris Cc: Pavel Machek , Len Brown , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Doug Anderson , Brian Norris , Jeffy Chen , linux-pm@vger.kernel.org, Chuansheng Liu , Dmitry Torokhov Subject: Re: [PATCH v2 2/2] PM / sleep: don't suspend parent when async child suspend_{noirq,late} fails Date: Tue, 01 Nov 2016 05:25:39 +0100 Message-ID: <8017823.VJuZzSqtaY@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.9.0-rc2+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1477584334-39956-1-git-send-email-briannorris@chromium.org> References: <1476923170-111986-2-git-send-email-briannorris@chromium.org> <1477584334-39956-1-git-send-email-briannorris@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, October 27, 2016 09:05:34 AM Brian Norris wrote: > Consider two devices, A and B, where B is a child of A, and B utilizes > asynchronous suspend (it does not matter whether A is sync or async). If > B fails to suspend_noirq() or suspend_late(), or is interrupted by a > wakeup (pm_wakeup_pending()), then it aborts and sets the async_error > variable. However, device A does not (immediately) check the async_error > variable; it may continue to run its own suspend_noirq()/suspend_late() > callback. This is bad. > > We can resolve this problem by checking the async_error flag after > waiting for children to suspend, using the same logic for the noirq and > late suspend cases as we already do for __device_suspend(). > > It's easy to observe this erroneous behavior by, for example, forcing a > device to sleep a bit in its suspend_noirq() (to ensure the parent is > waiting for the child to complete), then return an error, and watch the > parent suspend_noirq() still get called. (Or similarly, fake a wakeup > event at the right (or is it wrong?) time.) > > Fixes: de377b397272 ("PM / sleep: Asynchronous threads for suspend_late") > Fixes: 28b6fd6e3779 ("PM / sleep: Asynchronous threads for suspend_noirq") > Reported-by: Jeffy Chen > Signed-off-by: Brian Norris > Reviewed-by: Dmitry Torokhov > --- > v2: s/early/late/ in commit message > > drivers/base/power/main.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index c58563581345..eaf6b53463a5 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -1040,6 +1040,9 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a > > dpm_wait_for_children(dev, async); > > + if (async_error) > + goto Complete; > + This is a second chech for async_error in this routine and is the first one really needed after adding this? > if (dev->pm_domain) { > info = "noirq power domain "; > callback = pm_noirq_op(&dev->pm_domain->ops, state); > @@ -1187,6 +1190,9 @@ static int __device_suspend_late(struct device *dev, pm_message_t state, bool as > > dpm_wait_for_children(dev, async); > > + if (async_error) > + goto Complete; > + Same question. > if (dev->pm_domain) { > info = "late power domain "; > callback = pm_late_early_op(&dev->pm_domain->ops, state); > Thanks, Rafael