linux-kernel - Re: [PATCH] PM / core: Fix direct_complete handling for devices with no callbacks

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Date:   Tue, 22 May 2018 13:23:40 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Thomas Martitz <kugel@...kbox.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Lukas Wunner <lukas@...ner.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] PM / core: Fix direct_complete handling for devices with no callbacks

On Tuesday, May 22, 2018 1:12:40 PM CEST Thomas Martitz wrote:
> Hello,
> 
> thanks for for your effort and the patch.
> 
> Is this eligible for stable?

Yes, it is.

Thanks,
Rafael


> Am 22.05.2018 um 13:02 schrieb Rafael J. Wysocki:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > 
> > Commit 08810a4119aa (PM / core: Add NEVER_SKIP and SMART_PREPARE
> > driver flags) inadvertently prevented the power.direct_complete flag
> > from being set for devices without PM callbacks and with disabled
> > runtime PM which also prevents power.direct_complete from being set
> > for their parents.  That led to problems including a resume crash on
> > HP ZBook 14u.
> > 
> > Restore the previous behavior by causing power.direct_complete to be
> > set for those devices again, but do that in a more direct way to
> > avoid overlooking that case in the future.
> > 
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=199693
> > Fixes: 08810a4119aa (PM / core: Add NEVER_SKIP and SMART_PREPARE driver flags)
> > Reported-by: Thomas Martitz <kugel@...kbox.org>
> > Tested-by: Thomas Martitz <kugel@...kbox.org>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> >   drivers/base/power/main.c |    7 +++----
> >   1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> > Index: linux-pm/drivers/base/power/main.c
> > ===================================================================
> > --- linux-pm.orig/drivers/base/power/main.c
> > +++ linux-pm/drivers/base/power/main.c
> > @@ -1920,10 +1920,8 @@ static int device_prepare(struct device
> >   
> >   	dev->power.wakeup_path = false;
> >   
> > -	if (dev->power.no_pm_callbacks) {
> > -		ret = 1;	/* Let device go direct_complete */
> > +	if (dev->power.no_pm_callbacks)
> >   		goto unlock;
> > -	}
> >   
> >   	if (dev->pm_domain)
> >   		callback = dev->pm_domain->ops.prepare;
> > @@ -1957,7 +1955,8 @@ unlock:
> >   	 */
> >   	spin_lock_irq(&dev->power.lock);
> >   	dev->power.direct_complete = state.event == PM_EVENT_SUSPEND &&
> > -		pm_runtime_suspended(dev) && ret > 0 &&
> > +		((pm_runtime_suspended(dev) && ret > 0) ||
> > +		 dev->power.no_pm_callbacks) &&
> >   		!dev_pm_test_driver_flags(dev, DPM_FLAG_NEVER_SKIP);
> >   	spin_unlock_irq(&dev->power.lock);
> >   	return 0;
> > 
> 
>