linux-kernel - Re: [PATCH] drm/panthor: Defer scheduler entitiy destruction to queue release

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Message-ID: <20250925102055.3e6c5703@fedora>
Date: Thu, 25 Sep 2025 10:20:55 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Adrián Larumbe <adrian.larumbe@...labora.com>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, Steven
 Price <steven.price@....com>, kernel@...labora.com, Liviu Dudau
 <liviu.dudau@....com>, 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>, Heiko Stuebner <heiko@...ech.de>
Subject: Re: [PATCH] drm/panthor: Defer scheduler entitiy destruction to
 queue release

On Fri, 19 Sep 2025 17:43:48 +0100
Adrián Larumbe <adrian.larumbe@...labora.com> wrote:

> Commit de8548813824 ("drm/panthor: Add the scheduler logical block")
> handled destruction of a group's queues' drm scheduler entities early
> into the group destruction procedure.
> 
> However, that races with the group submit ioctl, because by the time
> entities are destroyed (through the group destroy ioctl), the submission
> procedure might've already obtained a group handle, and therefore the
> ability to push jobs into entities. This is met with a DRM error message
> within the drm scheduler core as a situation that should never occur.
> 
> Fix by deferring drm scheduler entity destruction to queue release time.
> 
> Fixes: de8548813824 ("drm/panthor: Add the scheduler logical block")
> Signed-off-by: Adrián Larumbe <adrian.larumbe@...labora.com>

Discussed with you before you posted it, so here's the official

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>

Thanks for fixing that.

Boris


> ---
>  drivers/gpu/drm/panthor/panthor_sched.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index 0cc9055f4ee5..f5e01cb16cfc 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -898,8 +898,7 @@ static void group_free_queue(struct panthor_group *group, struct panthor_queue *
>  	if (IS_ERR_OR_NULL(queue))
>  		return;
>  
> -	if (queue->entity.fence_context)
> -		drm_sched_entity_destroy(&queue->entity);
> +	drm_sched_entity_destroy(&queue->entity);
>  
>  	if (queue->scheduler.ops)
>  		drm_sched_fini(&queue->scheduler);
> @@ -3609,11 +3608,6 @@ int panthor_group_destroy(struct panthor_file *pfile, u32 group_handle)
>  	if (!group)
>  		return -EINVAL;
>  
> -	for (u32 i = 0; i < group->queue_count; i++) {
> -		if (group->queues[i])
> -			drm_sched_entity_destroy(&group->queues[i]->entity);
> -	}
> -
>  	mutex_lock(&sched->reset.lock);
>  	mutex_lock(&sched->lock);
>  	group->destroyed = true;