[PATCH 2/2] drm/sched: fix dropping the last fence ref

[Rob Clark]

On Tue, Nov 16, 2021 at 8:37 AM Daniel Vetter <daniel at ffwll.ch> wrote:
>
> On Tue, Nov 16, 2021 at 10:25:19AM +0100, Christian König wrote:
> > We need to grab another ref before trying to add the fence to the sched
> > job and not after.
> >
> > Signed-off-by: Christian König <christian.koenig at amd.com>
>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>
> I wondered first why this goes boom, but then I realized that in some
> cases add_dependency() drops the reference of the passed-in fence.
>
> Please also add the Fixes: line like in the previous patch.

oh, I sent https://patchwork.freedesktop.org/patch/463329/ before I
saw this.. it already has the fixes tag, and IMO a better description,
so I think you can just pick that one instead

BR,
-R

> Cheers, Daniel
>
> > ---
> >  drivers/gpu/drm/scheduler/sched_main.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> > index 94fe51b3caa2..400d201c3c28 100644
> > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > @@ -704,12 +704,14 @@ int drm_sched_job_add_implicit_dependencies(struct drm_sched_job *job,
> >       int ret;
> >
> >       dma_resv_for_each_fence(&cursor, obj->resv, write, fence) {
> > -             ret = drm_sched_job_add_dependency(job, fence);
> > -             if (ret)
> > -                     return ret;
> > -
> >               /* Make sure to grab an additional ref on the added fence */
> >               dma_fence_get(fence);
> > +
> > +             ret = drm_sched_job_add_dependency(job, fence);
> > +             if (ret) {
> > +                     dma_fence_put(fence);
> > +                     return ret;
> > +             }
> >       }
> >       return 0;
> >  }
> > --
> > 2.25.1
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch