linux-kernel - Re: [PATCH 2/2] drivers: cpuidle: add driver/device checks in cpuidle_enter

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Date:	Wed, 25 Feb 2015 14:56:46 +0000
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH 2/2] drivers: cpuidle: add driver/device checks in
 cpuidle_enter_freeze()

On Wed, Feb 25, 2015 at 02:30:49PM +0000, Daniel Lezcano wrote:

[...]

> > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> > index f47edc6c..344fe6c 100644
> > --- a/drivers/cpuidle/cpuidle.c
> > +++ b/drivers/cpuidle/cpuidle.c
> > @@ -44,6 +44,12 @@ void disable_cpuidle(void)
> >   	off = 1;
> >   }
> >
> > +static bool cpuidle_device_disabled(struct cpuidle_driver *drv,
> > +				    struct cpuidle_device *dev)
> > +{
> > +	return (off || !initialized || !drv || !dev || !dev->enabled);
> > +}
> 
> This is getting a bit fuzzy IMO. What means disabled ? :)
> 
> >   /**
> >    * cpuidle_play_dead - cpu off-lining
> >    *
> > @@ -124,6 +130,11 @@ void cpuidle_enter_freeze(void)
> >   	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> >   	int index;
> 
> I think this is exploding before because of dev == NULL in the line above.

Actually not, cpuidle_get_cpu_driver() checks the dev pointer, so
we might end up with drv == NULL and dev == NULL, and the check I added
still applies and it is effective I think.

Lorenzo
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