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

Bjørn Mork
2015-03-09T11:06:47Z

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.

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

Bjørn