Re: [PATCH v2] drm/sched: Use struct for drm_sched_init() params

[Danilo Krummrich <dakr@redhat.com>]

On Tue, Jan 28, 2025 at 03:29:27PM +0100, Philipp Stanner wrote:
> drm_sched_init() has a great many parameters and upcoming new
> functionality for the scheduler might add even more. Generally, the
> great number of parameters reduces readability and has already caused
> one missnaming in:
> 
> commit 6f1cacf4eba7 ("drm/nouveau: Improve variable name in nouveau_sched_init()").
> 
> Introduce a new struct for the scheduler init parameters and port all
> users.
> 
> Signed-off-by: Philipp Stanner <phasta@kernel.org>
> ---
> Changes in v2:
>   - Point out that the hang-limit is deprecated. (Christian)
>   - Initialize the structs to 0 at declaration. (Planet Earth)
>   - Don't set stuff explicitly to 0 / NULL. (Tvrtko)
>   - Make the structs const where possible. (Boris)
>   - v3d: Use just 1, universal, function for sched-init. (Maíra)
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 18 ++++--
>  drivers/gpu/drm/etnaviv/etnaviv_sched.c    | 20 +++----
>  drivers/gpu/drm/imagination/pvr_queue.c    | 18 ++++--
>  drivers/gpu/drm/lima/lima_sched.c          | 16 +++--
>  drivers/gpu/drm/msm/msm_ringbuffer.c       | 17 +++---
>  drivers/gpu/drm/nouveau/nouveau_sched.c    | 15 +++--
>  drivers/gpu/drm/panfrost/panfrost_job.c    | 20 ++++---
>  drivers/gpu/drm/panthor/panthor_mmu.c      | 16 +++--
>  drivers/gpu/drm/panthor/panthor_sched.c    | 29 +++++----
>  drivers/gpu/drm/scheduler/sched_main.c     | 50 ++++++----------
>  drivers/gpu/drm/v3d/v3d_sched.c            | 68 +++++++++-------------
>  drivers/gpu/drm/xe/xe_execlist.c           | 16 +++--
>  drivers/gpu/drm/xe/xe_gpu_scheduler.c      | 17 +++++-
>  include/drm/gpu_scheduler.h                | 37 ++++++++++--
>  14 files changed, 206 insertions(+), 151 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_sched.c b/drivers/gpu/drm/nouveau/nouveau_sched.c
> index 4412f2711fb5..b5aac8eebfdd 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_sched.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_sched.c
> @@ -404,7 +404,15 @@ nouveau_sched_init(struct nouveau_sched *sched, struct nouveau_drm *drm,
>  {
>  	struct drm_gpu_scheduler *drm_sched = &sched->base;
>  	struct drm_sched_entity *entity = &sched->entity;
> -	const long timeout = msecs_to_jiffies(NOUVEAU_SCHED_JOB_TIMEOUT_MS);
> +	const struct drm_sched_init_args args = {
> +		.ops = &nouveau_sched_ops,
> +		.submit_wq = wq,
> +		.num_rqs = DRM_SCHED_PRIORITY_COUNT,
> +		.credit_limit = credit_limit,
> +		.timeout = msecs_to_jiffies(NOUVEAU_SCHED_JOB_TIMEOUT_MS),
> +		.name = "nouveau_sched",
> +		.dev = drm->dev->dev
> +	};
>  	int ret;
>  
>  	if (!wq) {
> @@ -416,10 +424,7 @@ nouveau_sched_init(struct nouveau_sched *sched, struct nouveau_drm *drm,
>  		sched->wq = wq;

This change breaks Nouveau, you need to set args.submit_wq here as well.

>  	}
>  
> -	ret = drm_sched_init(drm_sched, &nouveau_sched_ops, wq,
> -			     NOUVEAU_SCHED_PRIORITY_COUNT,
> -			     credit_limit, 0, timeout,
> -			     NULL, NULL, "nouveau_sched", drm->dev->dev);
> +	ret = drm_sched_init(drm_sched, &args);
>  	if (ret)
>  		goto fail_wq;
>  
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index 5844a7f639e0..44713cfdcd74 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -3284,6 +3284,22 @@ static struct panthor_queue *
>  group_create_queue(struct panthor_group *group,
>  		   const struct drm_panthor_queue_create *args)
>  {
> +	const struct drm_sched_init_args sched_args = {
> +		.ops = &panthor_queue_sched_ops,
> +		.submit_wq = group->ptdev->scheduler->wq,
> +		.num_rqs = 1,
> +		/*
> +		 * The credit limit argument tells us the total number of
> +		 * instructions across all CS slots in the ringbuffer, with
> +		 * some jobs requiring twice as many as others, depending on
> +		 * their profiling status.
> +		 */
> +		.credit_limit = args->ringbuf_size / sizeof(u64),
> +		.timeout = msecs_to_jiffies(JOB_TIMEOUT_MS),
> +		.timeout_wq = group->ptdev->reset.wq,
> +		.name = "panthor-queue",
> +		.dev = group->ptdev->base.dev
> +	};
>  	struct drm_gpu_scheduler *drm_sched;
>  	struct panthor_queue *queue;
>  	int ret;
> @@ -3354,17 +3370,8 @@ group_create_queue(struct panthor_group *group,
>  	if (ret)
>  		goto err_free_queue;
>  
> -	/*
> -	 * Credit limit argument tells us the total number of instructions
> -	 * across all CS slots in the ringbuffer, with some jobs requiring
> -	 * twice as many as others, depending on their profiling status.
> -	 */
> -	ret = drm_sched_init(&queue->scheduler, &panthor_queue_sched_ops,
> -			     group->ptdev->scheduler->wq, 1,
> -			     args->ringbuf_size / sizeof(u64),
> -			     0, msecs_to_jiffies(JOB_TIMEOUT_MS),
> -			     group->ptdev->reset.wq,
> -			     NULL, "panthor-queue", group->ptdev->base.dev);
> +

This creates two empty lines.

> +	ret = drm_sched_init(&queue->scheduler, &sched_args);
>  	if (ret)
>  		goto err_free_queue;
>  
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> index a48be16ab84f..6295b2654a7c 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -1244,40 +1244,24 @@ static void drm_sched_run_job_work(struct work_struct *w)
>   * drm_sched_init - Init a gpu scheduler instance
>   *
>   * @sched: scheduler instance
> - * @ops: backend operations for this scheduler
> - * @submit_wq: workqueue to use for submission. If NULL, an ordered wq is
> - *	       allocated and used
> - * @num_rqs: number of runqueues, one for each priority, up to DRM_SCHED_PRIORITY_COUNT
> - * @credit_limit: the number of credits this scheduler can hold from all jobs
> - * @hang_limit: number of times to allow a job to hang before dropping it
> - * @timeout: timeout value in jiffies for the scheduler
> - * @timeout_wq: workqueue to use for timeout work. If NULL, the system_wq is
> - *		used
> - * @score: optional score atomic shared with other schedulers
> - * @name: name used for debugging
> - * @dev: target &struct device
> + * @args: scheduler initialization arguments
>   *
>   * Return 0 on success, otherwise error code.
>   */
> -int drm_sched_init(struct drm_gpu_scheduler *sched,
> -		   const struct drm_sched_backend_ops *ops,
> -		   struct workqueue_struct *submit_wq,
> -		   u32 num_rqs, u32 credit_limit, unsigned int hang_limit,
> -		   long timeout, struct workqueue_struct *timeout_wq,
> -		   atomic_t *score, const char *name, struct device *dev)
> +int drm_sched_init(struct drm_gpu_scheduler *sched, const struct drm_sched_init_args *args)
>  {
>  	int i;
>  
> -	sched->ops = ops;
> -	sched->credit_limit = credit_limit;
> -	sched->name = name;
> -	sched->timeout = timeout;
> -	sched->timeout_wq = timeout_wq ? : system_wq;
> -	sched->hang_limit = hang_limit;
> -	sched->score = score ? score : &sched->_score;
> -	sched->dev = dev;
> +	sched->ops = args->ops;
> +	sched->credit_limit = args->credit_limit;
> +	sched->name = args->name;
> +	sched->timeout = args->timeout;
> +	sched->timeout_wq = args->timeout_wq ? : system_wq;
> +	sched->hang_limit = args->hang_limit;
> +	sched->score = args->score ? args->score : &sched->_score;
> +	sched->dev = args->dev;
>  
> -	if (num_rqs > DRM_SCHED_PRIORITY_COUNT) {
> +	if (args->num_rqs > DRM_SCHED_PRIORITY_COUNT) {
>  		/* This is a gross violation--tell drivers what the  problem is.
>  		 */
>  		drm_err(sched, "%s: num_rqs cannot be greater than DRM_SCHED_PRIORITY_COUNT\n",
> @@ -1292,16 +1276,16 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
>  		return 0;
>  	}
>  
> -	if (submit_wq) {
> -		sched->submit_wq = submit_wq;
> +	if (args->submit_wq) {
> +		sched->submit_wq = args->submit_wq;
>  		sched->own_submit_wq = false;
>  	} else {
>  #ifdef CONFIG_LOCKDEP
> -		sched->submit_wq = alloc_ordered_workqueue_lockdep_map(name,
> +		sched->submit_wq = alloc_ordered_workqueue_lockdep_map(args->name,
>  								       WQ_MEM_RECLAIM,
>  								       &drm_sched_lockdep_map);
>  #else
> -		sched->submit_wq = alloc_ordered_workqueue(name, WQ_MEM_RECLAIM);
> +		sched->submit_wq = alloc_ordered_workqueue(args->name, WQ_MEM_RECLAIM);
>  #endif
>  		if (!sched->submit_wq)
>  			return -ENOMEM;
> @@ -1309,11 +1293,11 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
>  		sched->own_submit_wq = true;
>  	}
>  
> -	sched->sched_rq = kmalloc_array(num_rqs, sizeof(*sched->sched_rq),
> +	sched->sched_rq = kmalloc_array(args->num_rqs, sizeof(*sched->sched_rq),
>  					GFP_KERNEL | __GFP_ZERO);
>  	if (!sched->sched_rq)
>  		goto Out_check_own;
> -	sched->num_rqs = num_rqs;
> +	sched->num_rqs = args->num_rqs;
>  	for (i = DRM_SCHED_PRIORITY_KERNEL; i < sched->num_rqs; i++) {
>  		sched->sched_rq[i] = kzalloc(sizeof(*sched->sched_rq[i]), GFP_KERNEL);
>  		if (!sched->sched_rq[i])
> diff --git a/drivers/gpu/drm/xe/xe_execlist.c b/drivers/gpu/drm/xe/xe_execlist.c
> index a8c416a48812..db1c52dcf1a6 100644
> --- a/drivers/gpu/drm/xe/xe_execlist.c
> +++ b/drivers/gpu/drm/xe/xe_execlist.c
> @@ -332,6 +332,15 @@ static const struct drm_sched_backend_ops drm_sched_ops = {
>  static int execlist_exec_queue_init(struct xe_exec_queue *q)
>  {
>  	struct drm_gpu_scheduler *sched;
> +	const struct drm_sched_init_args args = {
> +		.ops = &drm_sched_ops,
> +		.num_rqs = 1,
> +		.credit_limit = q->lrc[0]->ring.size / MAX_JOB_SIZE_BYTES,
> +		.hang_limit = XE_SCHED_HANG_LIMIT,
> +		.timeout = XE_SCHED_JOB_TIMEOUT,
> +		.name = q->hwe->name,
> +		.dev = gt_to_xe(q->gt)->drm.dev
> +	};
>  	struct xe_execlist_exec_queue *exl;
>  	struct xe_device *xe = gt_to_xe(q->gt);
>  	int err;
> @@ -346,11 +355,8 @@ static int execlist_exec_queue_init(struct xe_exec_queue *q)
>  
>  	exl->q = q;
>  
> -	err = drm_sched_init(&exl->sched, &drm_sched_ops, NULL, 1,
> -			     q->lrc[0]->ring.size / MAX_JOB_SIZE_BYTES,
> -			     XE_SCHED_HANG_LIMIT, XE_SCHED_JOB_TIMEOUT,
> -			     NULL, NULL, q->hwe->name,
> -			     gt_to_xe(q->gt)->drm.dev);
> +

Two empty lines here as well.

> +	err = drm_sched_init(&exl->sched, &args);
>  	if (err)
>  		goto err_free;
>  
> diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.c b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> index 50361b4638f9..be95f4cca007 100644
> --- a/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> @@ -63,13 +63,24 @@ int xe_sched_init(struct xe_gpu_scheduler *sched,
>  		  atomic_t *score, const char *name,
>  		  struct device *dev)
>  {
> +	const struct drm_sched_init_args args = {
> +		.ops = ops,
> +		.submit_wq = submit_wq,
> +		.num_rqs = 1,
> +		.credit_limit = hw_submission,
> +		.hang_limit = hang_limit,
> +		.timeout = timeout,
> +		.timeout_wq = timeout_wq,
> +		.score = score,
> +		.name = name,
> +		.dev = dev
> +	};
> +
>  	sched->ops = xe_ops;
>  	INIT_LIST_HEAD(&sched->msgs);
>  	INIT_WORK(&sched->work_process_msg, xe_sched_process_msg_work);
>  
> -	return drm_sched_init(&sched->base, ops, submit_wq, 1, hw_submission,
> -			      hang_limit, timeout, timeout_wq, score, name,
> -			      dev);
> +	return drm_sched_init(&sched->base, &args);
>  }
>  
>  void xe_sched_fini(struct xe_gpu_scheduler *sched)
> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> index a0ff08123f07..f0f5435598a8 100644
> --- a/include/drm/gpu_scheduler.h
> +++ b/include/drm/gpu_scheduler.h
> @@ -540,12 +540,39 @@ struct drm_gpu_scheduler {
>  	struct device			*dev;
>  };
>  
> +/**
> + * struct drm_sched_init_args - parameters for initializing a DRM GPU scheduler
> + *
> + * @ops: backend operations provided by the driver
> + * @submit_wq: workqueue to use for submission. May be NULL.
> + *	If NULL, an ordered wq is allocated and used.
> + * @num_rqs: Number of run-queues. This may be at most DRM_SCHED_PRIORITY_COUNT,
> + *	as there's usually one run-queue per priority, but may be less.
> + * @credit_limit: the number of credits this scheduler can hold from all jobs
> + * @hang_limit: number of times to allow a job to hang before dropping it.
> + *	This mechanism is DEPRECATED. Set it to 0.
> + * @timeout: timeout value in jiffies for the scheduler
> + * @timeout_wq: workqueue to use for timeout work. May be NULL.
> + *	If NULL, the system_wq is used.
> + * @score: score atomic shared with other schedulers. May be NULL.
> + * @name: name used for debugging
> + * @dev: associated device. Used for debugging
> + */

This is weirdly formatted. Please align line breaks with the corresponding
number of spaces.

> +struct drm_sched_init_args {
> +	const struct drm_sched_backend_ops *ops;
> +	struct workqueue_struct *submit_wq;
> +	struct workqueue_struct *timeout_wq;
> +	u32 num_rqs;
> +	u32 credit_limit;
> +	unsigned int hang_limit;
> +	long timeout;
> +	atomic_t *score;
> +	const char *name;
> +	struct device *dev;
> +};
> +
>  int drm_sched_init(struct drm_gpu_scheduler *sched,
> -		   const struct drm_sched_backend_ops *ops,
> -		   struct workqueue_struct *submit_wq,
> -		   u32 num_rqs, u32 credit_limit, unsigned int hang_limit,
> -		   long timeout, struct workqueue_struct *timeout_wq,
> -		   atomic_t *score, const char *name, struct device *dev);
> +		const struct drm_sched_init_args *args);
>  
>  void drm_sched_fini(struct drm_gpu_scheduler *sched);
>  int drm_sched_job_init(struct drm_sched_job *job,
> -- 
> 2.47.1
>