[Intel-gfx] [PATCH v2 2/2] Test case for drm_vblank_cleanup refcount validation patch

[PrasannaKumar Muralidharan]

Hi Daniel,

On 1 November 2017 at 14:23, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Wed, Nov 01, 2017 at 09:48:28AM +0530, PrasannaKumar Muralidharan wrote:
>> Hi Daniel,
>>
>> On 31 October 2017 at 21:57, Daniel Vetter <daniel at ffwll.ch> wrote:
>> > On Tue, Oct 31, 2017 at 08:37:21PM +0530, PrasannaKumar Muralidharan wrote:
>> >> My patch is supposed to catch problem with drivers. It warns when
>> >> vblank refcount is non-zero in drm_vblank_cleanup call. From CI log it
>> >> can be seen that warning being triggered. I feel that my patch is
>> >> exposing existing issue.
>> >>
>> >> If I misinterpreted something please let me know.
>> >
>> > This is probably what's happening, but I can't merge a patch that breaks
>> > CI. So we need to track down that issue before merging.
>>
>> I understand. Being new to DRM subsystem I don't know if I can
>> contribute in finding the issue. I would be able to help if I could
>> get some guidance.
>
> If you have an intel laptop anywhere at hand that you could use to
> reproduce the issue, that would be a good start.

I do have one but it is my primary machine.

> Then go through the setup for the kms/drm validation suite:
>
> https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#testing-and-validation
>
> That should allow you to locally reproduce the issue (it seems to affect
> many machines, so I'd assume it doesn't matter which one you have).

If this setup is going to affect my normal workflow setup I would
prefer not to use it.

> Once you can reproduce it should be doable to figure out where we leak
> this reference (but usually it's a bit of hard work).

Anyway I will give it a try and see how far I can go.

> Btw I discussed your patch a bit on irc, a first step would be to also
> print the refcount when it's leaked, not just warn about it. Knowing how
> many references are leaked is sometimes a good hint about what's going on.

I will send a v4.

> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

Regards,
PrasannaKumar