Re: [PATCH 1/8] drm/panfrost: Make panfrost_job_run() return an ERR_PTR() instead of NULL

[Boris Brezillon <boris.brezillon@collabora.com>]

On Fri, 29 Nov 2019 14:19:50 +0000
Steven Price <steven.price@arm.com> wrote:

> On 29/11/2019 13:59, Boris Brezillon wrote:
> > If we don't do that, dma_fence_set_error() complains (called from
> > drm_sched_main()).
> > 
> > Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>  
> 
> This might be worth doing, but actually it's not Panfrost that is broken
> it's the callers, see [1] and [2]. So I don't think we want the
> Fixes/stable tag.

Okay.

> 
> [1] https://patchwork.kernel.org/patch/11218399/
> [2] https://patchwork.kernel.org/patch/11267073/
> 
> > ---
> >  drivers/gpu/drm/panfrost/panfrost_job.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> > index 21f34d44aac2..cdd9448fbbdd 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> > @@ -328,13 +328,13 @@ static struct dma_fence *panfrost_job_run(struct drm_sched_job *sched_job)
> >  	struct dma_fence *fence = NULL;
> >  
> >  	if (unlikely(job->base.s_fence->finished.error))
> > -		return NULL;
> > +		return ERR_PTR(job->base.s_fence->finished.error);

Hm, so we can keep the return NULL here if [1] is applied (the error
is preserved), but I'm not sure it's clearer that way.

> >  
> >  	pfdev->jobs[slot] = job;
> >  
> >  	fence = panfrost_fence_create(pfdev, slot);
> >  	if (IS_ERR(fence))
> > -		return NULL;
> > +		return ERR_PTR(-ENOMEM);  

This one should be fixed though, otherwise the error is never updated,
so I'm wondering if it doesn't deserve a Fixes tag in the end...

> 
> Why override the error from panfrost_fence_create? In this case we can just:
> 
> 	return fence;

Indeed.

> 
> Steve
> 
> >  
> >  	if (job->done_fence)
> >  		dma_fence_put(job->done_fence);
> >   
>