[PATCH] drm/v3d: fix sched job resources cleanup when a job is aborted

[Melissa Wen]

On 09/17, Iago Toral wrote:
> Reviewed-by: Iago Toral Quiroga <itoral at igalia.com>
> 
> With that said, I don't like how we are doing error handling here, I
> think we want to simplify this and try to make it so we centralize
> error handling in one place instead of having multiple error exits
> paths, each one trying to do the right thing at that point. This is
> error prone, as this patch is showing.
> 
> Here is a proposal to make this better:
> 
> Make job memory allocation part of v3d_job_init. v3d_job init already
> handles error conditions nicely. If we do this, we no longer need to
> handle allocation errors in ioctls one by one and for any job we only
> have two scenarios: v3d_job_init was successul or it failed (in which
> case we know it already cleaned up after itself and we should have a
> NULL job as a result). If v3d_job_init failed, then we *always* jump to
> the fail tag and there we call v3d_job_cleanup for all jobs that can be
> created in that ioctl. If a job is NULL then v3d_job_cleanup returns
> early, otherwise, we know it is a fully initialized job, so it does 	
> drm_sched_job_cleanup + v3d_job_put.
> 
> I think that should make error handling in these functions a lot
> easier.

Hi,

yes, sounds good. I can include this refactoring in the v2 of the
multisync patchset, since there is a prep work there (first patch).

Thanks for reviewing both,

Melissa

> 
> Iago
> 
> 
> On Thu, 2021-09-16 at 22:27 +0100, Melissa Wen wrote:
> > In a cl submission, when bin job initialization fails, sched job
> > resources
> > were already allocated for the render job. At this point,
> > drm_sched_job_init(render) was done in v3d_job_init but the render
> > job is
> > aborted before drm_sched_job_arm (in v3d_job_push) happens;
> > therefore, not
> > only v3d_job_put but also drm_sched_job_cleanup should be called (by
> > v3d_job_cleanup). A similar issue is addressed for csd and tfu
> > submissions.
> > 
> > The issue was noticed from a review by Iago Toral in a patch that
> > touches
> > the same part of the code.
> > 
> > Fixes: 916044fac8623 ("drm/v3d: Move drm_sched_job_init to
> > v3d_job_init")
> > Signed-off-by: Melissa Wen <mwen at igalia.com>
> > ---
> >  drivers/gpu/drm/v3d/v3d_gem.c | 11 +++++------
> >  1 file changed, 5 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/v3d/v3d_gem.c
> > b/drivers/gpu/drm/v3d/v3d_gem.c
> > index 1953706bdaeb..ead0be8d48a7 100644
> > --- a/drivers/gpu/drm/v3d/v3d_gem.c
> > +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> > @@ -567,14 +567,14 @@ v3d_submit_cl_ioctl(struct drm_device *dev,
> > void *data,
> >  	if (args->bcl_start != args->bcl_end) {
> >  		bin = kcalloc(1, sizeof(*bin), GFP_KERNEL);
> >  		if (!bin) {
> > -			v3d_job_put(&render->base);
> > +			v3d_job_cleanup(&render->base);
> > 
> > >  			return -ENOMEM;
> >  		}
> >  
> >  		ret = v3d_job_init(v3d, file_priv, &bin->base,
> >  				   v3d_job_free, args->in_sync_bcl,
> > V3D_BIN);
> >  		if (ret) {
> > -			v3d_job_put(&render->base);
> > +			v3d_job_cleanup(&render->base);
> >  			kfree(bin);
> >  			return ret;
> >  		}
> > @@ -716,7 +716,7 @@ v3d_submit_tfu_ioctl(struct drm_device *dev, void
> > *data,
> >  	job->base.bo = kcalloc(ARRAY_SIZE(args->bo_handles),
> >  			       sizeof(*job->base.bo), GFP_KERNEL);
> >  	if (!job->base.bo) {
> > -		v3d_job_put(&job->base);
> > +		v3d_job_cleanup(&job->base);
> >  		return -ENOMEM;
> >  	}
> >  
> > @@ -810,14 +810,13 @@ v3d_submit_csd_ioctl(struct drm_device *dev,
> > void *data,
> >  
> >  	clean_job = kcalloc(1, sizeof(*clean_job), GFP_KERNEL);
> >  	if (!clean_job) {
> > -		v3d_job_put(&job->base);
> > -		kfree(job);
> > +		v3d_job_cleanup(&job->base);
> >  		return -ENOMEM;
> >  	}
> >  
> >  	ret = v3d_job_init(v3d, file_priv, clean_job, v3d_job_free, 0,
> > V3D_CACHE_CLEAN);
> >  	if (ret) {
> > -		v3d_job_put(&job->base);
> > +		v3d_job_cleanup(&job->base);
> >  		kfree(clean_job);
> >  		return ret;
> >  	}
> 
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