Re: [PATCH v5 05/32] drm/xe/bo: Introduce xe_bo_put_async

["Ghimiray, Himal Prasad" <himal.prasad.ghimiray@intel.com>]

On 13-02-2025 07:40, Matthew Brost wrote:
> From: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> 
> Introduce xe_bo_put_async to put a bo where the context is such that
> the bo destructor can't run due to lockdep problems or atomic context.
> 
> If the put is the final put, freeing will be done from a work item.
> 
> v5:
>   - Kerenl doc for xe_bo_put_async (Thomas)
> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_bo.c           | 25 +++++++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_bo.h           | 19 +++++++++++++++++++
>   drivers/gpu/drm/xe/xe_device.c       |  3 +++
>   drivers/gpu/drm/xe/xe_device_types.h |  8 ++++++++
>   4 files changed, 55 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index cd1c693c0b62..a2a924b531e5 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -2644,6 +2644,31 @@ void xe_bo_put_commit(struct llist_head *deferred)
>   		drm_gem_object_free(&bo->ttm.base.refcount);
>   }
>   
> +static void xe_bo_dev_work_func(struct work_struct *work)
> +{
> +	struct xe_bo_dev *bo_dev = container_of(work, typeof(*bo_dev), async_free);
> +
> +	xe_bo_put_commit(&bo_dev->async_list);
> +}
> +
> +/**
> + * xe_bo_dev_init() - Initialize BO dev to manage async BO freeing
> + * @bo_dev: The BO dev structure
> + */
> +void xe_bo_dev_init(struct xe_bo_dev *bo_dev)
> +{
> +	INIT_WORK(&bo_dev->async_free, xe_bo_dev_work_func);
> +}
> +
> +/**
> + * xe_bo_dev_fini() - Finalize BO dev managing async BO freeing
> + * @bo_dev: The BO dev structure
> + */
> +void xe_bo_dev_fini(struct xe_bo_dev *bo_dev)
> +{
> +	flush_work(&bo_dev->async_free);
> +}
> +
>   void xe_bo_put(struct xe_bo *bo)
>   {
>   	struct xe_tile *tile;
> diff --git a/drivers/gpu/drm/xe/xe_bo.h b/drivers/gpu/drm/xe/xe_bo.h
> index f09b9315721b..9dfec438d1c7 100644
> --- a/drivers/gpu/drm/xe/xe_bo.h
> +++ b/drivers/gpu/drm/xe/xe_bo.h
> @@ -322,6 +322,25 @@ xe_bo_put_deferred(struct xe_bo *bo, struct llist_head *deferred)
>   
>   void xe_bo_put_commit(struct llist_head *deferred);
>   
> +/**
> + * xe_bo_put_async() - Put BO async
> + * @bo: The bo to put.
> + *
> + * Put BO async, the final put is deferred to a worker to exit an IRQ context.
> + */
> +static inline void
> +xe_bo_put_async(struct xe_bo *bo)
> +{
> +	struct xe_bo_dev *bo_device = &xe_bo_device(bo)->bo_device;
> +
> +	if (xe_bo_put_deferred(bo, &bo_device->async_list))
> +		schedule_work(&bo_device->async_free);
> +}
> +
> +void xe_bo_dev_init(struct xe_bo_dev *bo_device);
> +
> +void xe_bo_dev_fini(struct xe_bo_dev *bo_device);
> +
>   struct sg_table *xe_bo_sg(struct xe_bo *bo);
>   
>   /*
> diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
> index 36d7ffb3b4d9..756099e870cd 100644
> --- a/drivers/gpu/drm/xe/xe_device.c
> +++ b/drivers/gpu/drm/xe/xe_device.c
> @@ -388,6 +388,8 @@ static void xe_device_destroy(struct drm_device *dev, void *dummy)
>   {
>   	struct xe_device *xe = to_xe_device(dev);
>   
> +	xe_bo_dev_fini(&xe->bo_device);
> +
>   	if (xe->preempt_fence_wq)
>   		destroy_workqueue(xe->preempt_fence_wq);
>   
> @@ -425,6 +427,7 @@ struct xe_device *xe_device_create(struct pci_dev *pdev,
>   	if (WARN_ON(err))
>   		goto err;
>   
> +	xe_bo_dev_init(&xe->bo_device);
>   	err = drmm_add_action_or_reset(&xe->drm, xe_device_destroy, NULL);
>   	if (err)
>   		goto err;
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 833c29fed3a3..6a41f608a7a1 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -525,6 +525,14 @@ struct xe_device {
>   		int mode;
>   	} wedged;
>   
> +	/** @bo_device: Struct to control async free of BOs */
> +	struct xe_bo_dev {
> +		/** @async_free: Free worker */
> +		struct work_struct async_free;
> +		/** @async_list: List of BOs to be freed */
> +		struct llist_head async_list;
> +	} bo_device;

LGTM
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>

> +
>   	/** @pmu: performance monitoring unit */
>   	struct xe_pmu pmu;
>