Re: [PATCH v4 05/33] drm/xe/bo: Introduce xe_bo_put_async

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Jan 30, 2025 at 09:49:54AM +0100, Thomas Hellström wrote:
> On Wed, 2025-01-29 at 11:51 -0800, 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.
> > 
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > ---
> >  drivers/gpu/drm/xe/xe_bo.c           | 25 +++++++++++++++++++++++++
> >  drivers/gpu/drm/xe/xe_bo.h           | 13 +++++++++++++
> >  drivers/gpu/drm/xe/xe_device.c       |  3 +++
> >  drivers/gpu/drm/xe/xe_device_types.h |  8 ++++++++
> >  4 files changed, 49 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> > index fb1629d9d566..e914a60b8afc 100644
> > --- a/drivers/gpu/drm/xe/xe_bo.c
> > +++ b/drivers/gpu/drm/xe/xe_bo.c
> > @@ -2544,6 +2544,31 @@ 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 04995c5ced32..ce55a2bb13f6 100644
> > --- a/drivers/gpu/drm/xe/xe_bo.h
> > +++ b/drivers/gpu/drm/xe/xe_bo.h
> > @@ -317,6 +317,19 @@ xe_bo_put_deferred(struct xe_bo *bo, struct
> > llist_head *deferred)
> >  
> >  void xe_bo_put_commit(struct llist_head *deferred);
> >  
> > +static inline void
> > +xe_bo_put_async(struct xe_bo *bo)
> 
> Needs kerneldoc. I will rebase my multi-device series on this one, Let
> me know if you'll add that or if I should do it when rebasing my multi-
> device series on this one.
> 

Yep. Added kernel for structures / exported functions but missed this
inline. I should be able to write something here.

Matt

> > +{
> > +	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 8fedc72e9db4..5fac3d40cc8e 100644
> > --- a/drivers/gpu/drm/xe/xe_device.c
> > +++ b/drivers/gpu/drm/xe/xe_device.c
> > @@ -387,6 +387,8 @@ 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);
> >  
> > @@ -424,6 +426,7 @@ 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 89f532b67bc4..71151532e28f 100644
> > --- a/drivers/gpu/drm/xe/xe_device_types.h
> > +++ b/drivers/gpu/drm/xe/xe_device_types.h
> > @@ -519,6 +519,14 @@ 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;
> > +
> >  	/** @pmu: performance monitoring unit */
> >  	struct xe_pmu pmu;
> >  
>