RE: [RFC][PATCH] omapfb: Condition mutex acquisition

Hiremath, Vaibhav
2009-09-29T18:26:34Z

> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
> owner@vger.kernel.org] On Behalf Of Aguirre Rodriguez, Sergio
> Alberto
> Sent: Tuesday, September 29, 2009 8:27 PM
> To: tomi.valkeinen@nokia.com
> Cc: Deak Imre (Nokia-D/Helsinki); linux-omap@vger.kernel.org
> Subject: RE: [RFC][PATCH] omapfb: Condition mutex acquisition
>
> From: Tomi Valkeinen [tomi.valkeinen@nokia.com]
> Sent: Tuesday, September 29, 2009 9:53 AM
> > On Tue, 2009-09-29 at 16:34 +0200, ext Aguirre Rodriguez, Sergio
> Alberto
> > wrote:
> > > From: Tomi Valkeinen [tomi.valkeinen@nokia.com]
> > > Sent: Tuesday, September 29, 2009 9:22 AM
> > > > On Tue, 2009-09-29 at 16:14 +0200, ext Aguirre Rodriguez,
> Sergio Alberto
> > > > wrote:
> > > > > From: Sergio Aguirre <saaguirre@ti.com>
> > > > >
> > > > > Acquiring mutex before framebuffer registration doesn't make
> sense,
> > > > > As there's no danger of external access to the memory
> related fields.
> > > >
> > > > What problem does this patch solve? It makes the code more
> complex.
> > > >
> > >
> > > Tomi,
> > >
> > > Thanks for your time.
> > >
> > > The problem was that, during platform driver registration,
> > > this sequence was executed:
> > >
> > > -> omapfb_probe
> > > -> omapfb_do_probe
> > > -> planes_init
> > > -> fbinfo_init
> > > -> set_fb_fix
> > > ...
> > > -> register_framebuffer
> > >
> > > And then, inside that function, an attempt of acquiring a
> > > mutex failed, because it wasn't initialized before trying it:
> > >
> > > mutex_lock(&fbi->mm_lock);
> > >
> > > It is actually initialized later in omapfb_do_probe in
> register_framebuffer call.
> > >
> > > So, how is the best to solve this then?
> >
> > Oh, I wasn't implying that there's something wrong with the fix, I
> just
> > didn't know what it was fixing =).
>
> Ok, no prob :) Should I improve the patch description?
> Any suggestion coming from an expert ;) ?
>
> >
> > Looks like a valid fix to me.
>
> Great! :) Once you're ok with the description, I can add your
> "Acked-by:" and
> send to linux-fb-devel ML. Would that be ok?
>
[Hiremath, Vaibhav] Hi Sergio,

I also think this is valid fix.

Tomi,

Don't you think we should also make use of mm_lock in new OMAP2 Fbdev driver, to be more specific and safer side?

Thanks,
Vaibhav

> Regards,
> Sergio
>
> >
> > Tomi
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