Re: [PATCH] uvcvideo: Don't call vb2 mmap and get_unmapped_area with queue lock held

Laurent Pinchart
2015-03-10T07:02:53Z

Hi Bjørn,

(it took me half an hour to figure out how to write ø on my keyboard :-))

On Monday 09 March 2015 12:06:36 Bjørn Mork wrote:
> Bjørn Mork <bjorn@mork.no> writes:
> > Laurent Pinchart <laurent.pinchart@ideasonboard.com> writes:
> >> Bjørn, does this fix the circular locking dependency you have reported in
> >> "[v3.19-rc7] possible circular locking dependency in uvc_queue_streamoff"
> >> ? The report mentions involves locks, so I'm not 100% this patch will fix
> >> the issue.
> >
> > Sorry, I forgot all about that report after firing it off... Should
> > have followed it up with some more details.
> >
> > Grepping my logs now I cannot find this warning at all after the one I
> > reported. I see it once before (while running 3.19-rc6). So it is
> > definitely not easily reproducible. And I have a bad feeling the
> > trigger might involve completely unrelated USB issues...
> >
> > In any case, thanks for the patch. I will test it for a while and let
> > you know if the same warning shows ut with it. But based on the rare
> > occurence, I don't think I ever will be able to positively confirm that
> > the warning is gone.
>
> FWIW, I have not seen the warning after applying this patch, so it
> appears to fix the problem. Thanks.

You're welcome.

> If I'm wrong, then I'm sure Murphy will tell us as soon as I send this
> email :-)

I'd be happy to prove Murphy wrong for once.

--
Regards,

Laurent Pinchart