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

Tony Lindgren
2009-09-30T00:53:09Z

* Tomi Valkeinen <tomi.valkeinen@nokia.com> [090929 07:54]:
> 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 =).
>
> Looks like a valid fix to me.

Tomi & Imre, do you want me to add this to the omap-fixes queue,
or are you planning to send other fixes too?

If you want me to add it, please reply with your ack.

I'll added it into omap-fixes-testing branch for now so we can
get the omaps booted.

Regards,

Tony