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

Aguirre Rodriguez, Sergio Alberto
2009-09-29T14:34:30Z

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?

BTW, this problem is found on current Linus tree, and in
current l-o tree aswell, and i saw it on my 3430SDP VG5.0.1.

Regards,
Sergio

> Tomi
>