linux-kernel - Re: [PATCH] drm/panthor: assign unique names to queues

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Message-ID: <20250829100021.361578c5@fedora>
Date: Fri, 29 Aug 2025 10:00:21 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Chia-I Wu <olvaffe@...il.com>
Cc: Steven Price <steven.price@....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>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/panthor: assign unique names to queues

On Thu, 28 Aug 2025 13:05:32 -0700
Chia-I Wu <olvaffe@...il.com> wrote:

> Userspace relies on the ring field of gpu_scheduler tracepoints to
> identify a drm_gpu_scheduler.  The value of the ring field is taken from
> sched->name.
> 
> Because we typically have multiple schedulers running in parallel in
> each process, assign unique names to schedulers such that userspace can
> distinguish them.
> 
> Signed-off-by: Chia-I Wu <olvaffe@...il.com>

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

Two minor comments below.

> ---
>  drivers/gpu/drm/panthor/panthor_sched.c | 32 ++++++++++++++++++-------
>  1 file changed, 23 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index ba5dc3e443d9c..26616b6cb110d 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -360,6 +360,9 @@ struct panthor_queue {
>  	/** @entity: DRM scheduling entity used for this queue. */
>  	struct drm_sched_entity entity;
>  
> +	/** @name: DRM scheduler name for this queue. */
> +	char name[32];
> +
>  	/**
>  	 * @remaining_time: Time remaining before the job timeout expires.
>  	 *
> @@ -3308,9 +3311,10 @@ static u32 calc_profiling_ringbuf_num_slots(struct panthor_device *ptdev,
>  
>  static struct panthor_queue *
>  group_create_queue(struct panthor_group *group,
> -		   const struct drm_panthor_queue_create *args)
> +		   const struct drm_panthor_queue_create *args, u32 gid,
> +		   u32 qid)
>  {
> -	const struct drm_sched_init_args sched_args = {
> +	struct drm_sched_init_args sched_args = {
>  		.ops = &panthor_queue_sched_ops,
>  		.submit_wq = group->ptdev->scheduler->wq,
>  		.num_rqs = 1,
> @@ -3323,7 +3327,7 @@ group_create_queue(struct panthor_group *group,
>  		.credit_limit = args->ringbuf_size / sizeof(u64),
>  		.timeout = msecs_to_jiffies(JOB_TIMEOUT_MS),
>  		.timeout_wq = group->ptdev->reset.wq,
> -		.name = "panthor-queue",
> +		.name = NULL, /* will point to queue->name */
>  		.dev = group->ptdev->base.dev,
>  	};
>  	struct drm_gpu_scheduler *drm_sched;
> @@ -3398,6 +3402,11 @@ group_create_queue(struct panthor_group *group,
>  	if (ret)
>  		goto err_free_queue;
>  
> +	/* assign a unique name */
> +	snprintf(queue->name, sizeof(queue->name), "panthor-queue-%d-%d", gid,
> +		 qid);
> +	sched_args.name = queue->name;

Should we plan ahead and have the pid in the name too?

> +
>  	ret = drm_sched_init(&queue->scheduler, &sched_args);
>  	if (ret)
>  		goto err_free_queue;
> @@ -3540,12 +3549,18 @@ int panthor_group_create(struct panthor_file *pfile,
>  	memset(group->syncobjs->kmap, 0,
>  	       group_args->queues.count * sizeof(struct panthor_syncobj_64b));
>  
> +	ret = xa_alloc(&gpool->xa, &gid, group,
> +		       XA_LIMIT(1, MAX_GROUPS_PER_POOL), GFP_KERNEL);
> +	if (ret)
> +		goto err_put_group;
> +
>  	for (i = 0; i < group_args->queues.count; i++) {
> -		group->queues[i] = group_create_queue(group, &queue_args[i]);
> +		group->queues[i] =
> +			group_create_queue(group, &queue_args[i], gid, i);

nit: the limit is 100 chars now, so I think we can have it on a single
line.

>  		if (IS_ERR(group->queues[i])) {
>  			ret = PTR_ERR(group->queues[i]);
>  			group->queues[i] = NULL;
> -			goto err_put_group;
> +			goto err_erase_gid;
>  		}
>  
>  		group->queue_count++;
> @@ -3553,10 +3568,6 @@ int panthor_group_create(struct panthor_file *pfile,
>  
>  	group->idle_queues = GENMASK(group->queue_count - 1, 0);
>  
> -	ret = xa_alloc(&gpool->xa, &gid, group, XA_LIMIT(1, MAX_GROUPS_PER_POOL), GFP_KERNEL);
> -	if (ret)
> -		goto err_put_group;
> -
>  	mutex_lock(&sched->reset.lock);
>  	if (atomic_read(&sched->reset.in_progress)) {
>  		panthor_group_stop(group);
> @@ -3575,6 +3586,9 @@ int panthor_group_create(struct panthor_file *pfile,
>  
>  	return gid;
>  
> +err_erase_gid:
> +	xa_erase(&gpool->xa, gid);
> +
>  err_put_group:
>  	group_put(group);
>  	return ret;