linux-kernel - Re: [PATCH] drm/sched: warn about drm_sched_job

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Message-ID: <243743c08eca2da4882d1c5fb3b01b68f044ee4a.camel@redhat.com>
Date: Fri, 25 Oct 2024 18:04:27 +0200
From: Philipp Stanner <pstanner@...hat.com>
To: Matthew Brost <matthew.brost@...el.com>
Cc: Luben Tuikov <ltuikov89@...il.com>, Danilo Krummrich <dakr@...nel.org>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
 <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
 <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Christian
 König <christian.koenig@....com>,  Tvrtko Ursulin
 <tursulin@...lia.com>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/sched: warn about drm_sched_job_init()'s partial
 init

On Fri, 2024-10-25 at 02:32 +0000, Matthew Brost wrote:
> On Wed, Oct 23, 2024 at 04:15:31PM +0200, Philipp Stanner wrote:
> > drm_sched_job_init()'s name suggests that after the function
> > succeeded,
> > parameter "job" will be fully initialized. This is not the case;
> > some
> > members are only later set, notably drm_sched_job.sched by
> > drm_sched_job_arm().
> > 
> > Document that drm_sched_job_init() does not set all struct members.
> > 
> > Document the lifetime of drm_sched_job.sched.
> > 
> > Signed-off-by: Philipp Stanner <pstanner@...hat.com>
> 
> Reviewed-by: Matthew Brost <matthew.brost@...el.com>
> 

Applied to drm-misc-next, thank you.

P.


> > ---
> >  drivers/gpu/drm/scheduler/sched_main.c | 4 ++++
> >  include/drm/gpu_scheduler.h            | 8 ++++++++
> >  2 files changed, 12 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/scheduler/sched_main.c
> > b/drivers/gpu/drm/scheduler/sched_main.c
> > index dab8cca79eb7..8c1c4739f36d 100644
> > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > @@ -771,6 +771,10 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs);
> >   * Drivers must make sure drm_sched_job_cleanup() if this function
> > returns
> >   * successfully, even when @job is aborted before
> > drm_sched_job_arm() is called.
> >   *
> > + * Note that this function does not assign a valid value to each
> > struct member
> > + * of struct drm_sched_job. Take a look at that struct's
> > documentation to see
> > + * who sets which struct member with what lifetime.
> > + *
> >   * WARNING: amdgpu abuses &drm_sched.ready to signal when the
> > hardware
> >   * has died, which can mean that there's no valid runqueue for a
> > @entity.
> >   * This function returns -ENOENT in this case (which probably
> > should be -EIO as
> > diff --git a/include/drm/gpu_scheduler.h
> > b/include/drm/gpu_scheduler.h
> > index ab161289d1bf..95e17504e46a 100644
> > --- a/include/drm/gpu_scheduler.h
> > +++ b/include/drm/gpu_scheduler.h
> > @@ -340,6 +340,14 @@ struct drm_sched_fence
> > *to_drm_sched_fence(struct dma_fence *f);
> >  struct drm_sched_job {
> >  	struct spsc_node		queue_node;
> >  	struct list_head		list;
> > +
> > +	/**
> > +	 * @sched:
> > +	 *
> > +	 * The scheduler this job is or will be scheduled on. Gets
> > set by
> > +	 * drm_sched_job_arm(). Valid until
> > drm_sched_backend_ops.free_job()
> > +	 * has finished.
> > +	 */
> >  	struct drm_gpu_scheduler	*sched;
> >  	struct drm_sched_fence		*s_fence;
> >  
> > -- 
> > 2.47.0
> > 
>