Re: [PATCH 24/51] drm/i915: Add i915_sched_engine destroy vfunc

[John Harrison <john.c.harrison@xxxxxxxxx>]

On 7/16/2021 13:16, Matthew Brost wrote:
> This help the backends clean up when the schedule engine object gets
help -> helps. Although, I would say it's more like 'this is required to 
allow backend specific cleanup'. It doesn't just make life a bit easier, 
it allows us to not leak stuff and/or dereference null pointers!

Either way...
Reviewed-by: John Harrison <John.C.Harrison@xxxxxxxxx>

> destroyed.
>
> Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/i915_scheduler.c       | 3 ++-
>   drivers/gpu/drm/i915/i915_scheduler.h       | 4 +---
>   drivers/gpu/drm/i915/i915_scheduler_types.h | 5 +++++
>   3 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
> index 3a58a9130309..4fceda96deed 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler.c
> +++ b/drivers/gpu/drm/i915/i915_scheduler.c
> @@ -431,7 +431,7 @@ void i915_request_show_with_schedule(struct drm_printer *m,
>   	rcu_read_unlock();
>   }
>   
> -void i915_sched_engine_free(struct kref *kref)
> +static void default_destroy(struct kref *kref)
>   {
>   	struct i915_sched_engine *sched_engine =
>   		container_of(kref, typeof(*sched_engine), ref);
> @@ -453,6 +453,7 @@ i915_sched_engine_create(unsigned int subclass)
>   
>   	sched_engine->queue = RB_ROOT_CACHED;
>   	sched_engine->queue_priority_hint = INT_MIN;
> +	sched_engine->destroy = default_destroy;
>   
>   	INIT_LIST_HEAD(&sched_engine->requests);
>   	INIT_LIST_HEAD(&sched_engine->hold);
> diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
> index 650ab8e0db9f..3c9504e9f409 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler.h
> +++ b/drivers/gpu/drm/i915/i915_scheduler.h
> @@ -51,8 +51,6 @@ static inline void i915_priolist_free(struct i915_priolist *p)
>   struct i915_sched_engine *
>   i915_sched_engine_create(unsigned int subclass);
>   
> -void i915_sched_engine_free(struct kref *kref);
> -
>   static inline struct i915_sched_engine *
>   i915_sched_engine_get(struct i915_sched_engine *sched_engine)
>   {
> @@ -63,7 +61,7 @@ i915_sched_engine_get(struct i915_sched_engine *sched_engine)
>   static inline void
>   i915_sched_engine_put(struct i915_sched_engine *sched_engine)
>   {
> -	kref_put(&sched_engine->ref, i915_sched_engine_free);
> +	kref_put(&sched_engine->ref, sched_engine->destroy);
>   }
>   
>   static inline bool
> diff --git a/drivers/gpu/drm/i915/i915_scheduler_types.h b/drivers/gpu/drm/i915/i915_scheduler_types.h
> index 5935c3152bdc..00384e2c5273 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler_types.h
> +++ b/drivers/gpu/drm/i915/i915_scheduler_types.h
> @@ -163,6 +163,11 @@ struct i915_sched_engine {
>   	 */
>   	void *private_data;
>   
> +	/**
> +	 * @destroy: destroy schedule engine / cleanup in backend
> +	 */
> +	void	(*destroy)(struct kref *kref);
> +
>   	/**
>   	 * @kick_backend: kick backend after a request's priority has changed
>   	 */