linux-kernel - Re: [PATCH] mfd: check for NULL platform data

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Message-ID: <20101126102339.GD5520@sortiz-mobl>
Date:	Fri, 26 Nov 2010 11:23:40 +0100
From:	Samuel Ortiz <sameo@...ux.intel.com>
To:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Cc:	Fabio Estevam <fabioestevam@...oo.com>,
	linux-kernel@...r.kernel.org, s.hauer@...gutronix.de
Subject: Re: [PATCH] mfd: check for NULL platform data

Hi Uwe,

On Thu, Nov 11, 2010 at 04:44:07PM +0100, Uwe Kleine-König wrote:
> Hi Fabio,
> 
> On Thu, Nov 11, 2010 at 06:58:14AM -0800, Fabio Estevam wrote:
> > Avoid kernel crash if platform data is NULL.
> > 
> > Signed-off-by: Fabio Estevam <fabio.estevam@...escale.com>
> > ---
> >  drivers/mfd/mc13xxx-core.c |    3 +++
> >  1 files changed, 3 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/mfd/mc13xxx-core.c b/drivers/mfd/mc13xxx-core.c
> > index a2ac2ed..b4d6bb1 100644
> > --- a/drivers/mfd/mc13xxx-core.c
> > +++ b/drivers/mfd/mc13xxx-core.c
> > @@ -757,6 +757,9 @@ err_revision:
> >  
> >  	mc13xxx_unlock(mc13xxx);
> >  
> > +	if (pdata == NULL)
> > +		return 0;
> > +
> I'm not sure it's really needed to catch this error.  Not passing pdata
> isn't sensible and then maybe failing with a bang is better than
> handling silently.
> 
> And if you want to break probing, do you really want to return 0, i.e.
> let the binding succeed?  IMHO (if you really want to handle pdata ==
> NULL) you should fail before allocating the private data with
> -ESOMETHINGSENSIBLE.
Agreed. Besides failing silently, Fabio's patch leaks the mc13xxx pointer and
doesn't free the requested IRQ line.
So NAK for now, although I wouldn't be against checking for a NULL pdata at
the very begining of the probe routine.

Cheers,
Samuel.

-- 
Intel Open Source Technology Centre
http://oss.intel.com/
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