Re: [PATCH v10 1/7] drm/ttm: Balance ttm_resource_cursor_init() and ttm_resource_cursor_fini()

["Christian König" <christian.koenig@amd.com>]

Am 16.09.24 um 16:51 schrieb Thomas Hellström:
> Make the interface more symmetric by providing and using a
> ttm_resource_cursor_init().
>
> v10:
> - Fix a stray newline (Matthew Brost)
> - Update kerneldoc (Matthew Brost)
>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/ttm/ttm_bo.c       |  3 ++-
>   drivers/gpu/drm/ttm/ttm_bo_util.c  |  3 ++-
>   drivers/gpu/drm/ttm/ttm_resource.c | 35 ++++++++++++++++++++----------
>   include/drm/ttm/ttm_resource.h     | 11 +++++-----
>   4 files changed, 34 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 320592435252..06a237d420dc 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -450,7 +450,8 @@ int ttm_bo_evict_first(struct ttm_device *bdev, struct ttm_resource_manager *man
>   	int ret = 0;
>   
>   	spin_lock(&bdev->lru_lock);
> -	res = ttm_resource_manager_first(man, &cursor);
> +	ttm_resource_cursor_init(&cursor, man);
> +	res = ttm_resource_manager_first(&cursor);
>   	ttm_resource_cursor_fini(&cursor);
>   	if (!res) {
>   		ret = -ENOENT;
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 3c07f4712d5c..454a51239614 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -865,7 +865,8 @@ s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev,
>   	s64 lret;
>   
>   	spin_lock(&bdev->lru_lock);
> -	ttm_resource_manager_for_each_res(man, &cursor, res) {
> +	ttm_resource_cursor_init(&cursor, man);
> +	ttm_resource_manager_for_each_res(&cursor, res) {
>   		struct ttm_buffer_object *bo = res->bo;
>   		bool bo_needs_unlock = false;
>   		bool bo_locked = false;
> diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
> index 6d764ba88aab..2b69229f127c 100644
> --- a/drivers/gpu/drm/ttm/ttm_resource.c
> +++ b/drivers/gpu/drm/ttm/ttm_resource.c
> @@ -80,6 +80,23 @@ static void ttm_bulk_move_drop_cursors(struct ttm_lru_bulk_move *bulk)
>   		ttm_resource_cursor_clear_bulk(cursor);
>   }
>   
> +/**
> + * ttm_resource_cursor_init() - Initialize a struct ttm_resource_cursor
> + * @cursor: The cursor to initialize.
> + * @man: The resource manager.
> + *
> + * Initialize the cursor before using it for iteration.
> + */
> +void ttm_resource_cursor_init(struct ttm_resource_cursor *cursor,
> +			      struct ttm_resource_manager *man)
> +{
> +	cursor->priority = 0;
> +	cursor->man = man;
> +	ttm_lru_item_init(&cursor->hitch, TTM_LRU_HITCH);
> +	INIT_LIST_HEAD(&cursor->bulk_link);
> +	INIT_LIST_HEAD(&cursor->hitch.link);
> +}
> +
>   /**
>    * ttm_resource_cursor_fini() - Finalize the LRU list cursor usage
>    * @cursor: The struct ttm_resource_cursor to finalize.
> @@ -577,7 +594,6 @@ ttm_resource_cursor_check_bulk(struct ttm_resource_cursor *cursor,
>   /**
>    * ttm_resource_manager_first() - Start iterating over the resources
>    * of a resource manager
> - * @man: resource manager to iterate over
>    * @cursor: cursor to record the position
>    *
>    * Initializes the cursor and starts iterating. When done iterating,
> @@ -586,17 +602,16 @@ ttm_resource_cursor_check_bulk(struct ttm_resource_cursor *cursor,
>    * Return: The first resource from the resource manager.
>    */
>   struct ttm_resource *
> -ttm_resource_manager_first(struct ttm_resource_manager *man,
> -			   struct ttm_resource_cursor *cursor)
> +ttm_resource_manager_first(struct ttm_resource_cursor *cursor)
>   {
> -	lockdep_assert_held(&man->bdev->lru_lock);
> +	struct ttm_resource_manager *man = cursor->man;
>   
> -	cursor->priority = 0;
> -	cursor->man = man;
> -	ttm_lru_item_init(&cursor->hitch, TTM_LRU_HITCH);
> -	INIT_LIST_HEAD(&cursor->bulk_link);
> -	list_add(&cursor->hitch.link, &man->lru[cursor->priority]);
> +	if (WARN_ON_ONCE(!man))
> +		return NULL;
> +
> +	lockdep_assert_held(&man->bdev->lru_lock);
>   
> +	list_move(&cursor->hitch.link, &man->lru[cursor->priority]);
>   	return ttm_resource_manager_next(cursor);
>   }
>   
> @@ -632,8 +647,6 @@ ttm_resource_manager_next(struct ttm_resource_cursor *cursor)
>   		ttm_resource_cursor_clear_bulk(cursor);
>   	}
>   
> -	ttm_resource_cursor_fini(cursor);
> -
>   	return NULL;
>   }
>   
> diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
> index be034be56ba1..e1f3b95d73b6 100644
> --- a/include/drm/ttm/ttm_resource.h
> +++ b/include/drm/ttm/ttm_resource.h
> @@ -325,6 +325,9 @@ struct ttm_resource_cursor {
>   	unsigned int priority;
>   };
>   
> +void ttm_resource_cursor_init(struct ttm_resource_cursor *cursor,
> +			      struct ttm_resource_manager *man);
> +
>   void ttm_resource_cursor_fini(struct ttm_resource_cursor *cursor);
>   
>   /**
> @@ -456,8 +459,7 @@ void ttm_resource_manager_debug(struct ttm_resource_manager *man,
>   				struct drm_printer *p);
>   
>   struct ttm_resource *
> -ttm_resource_manager_first(struct ttm_resource_manager *man,
> -			   struct ttm_resource_cursor *cursor);
> +ttm_resource_manager_first(struct ttm_resource_cursor *cursor);
>   struct ttm_resource *
>   ttm_resource_manager_next(struct ttm_resource_cursor *cursor);
>   
> @@ -466,14 +468,13 @@ ttm_lru_first_res_or_null(struct list_head *head);
>   
>   /**
>    * ttm_resource_manager_for_each_res - iterate over all resources
> - * @man: the resource manager
>    * @cursor: struct ttm_resource_cursor for the current position
>    * @res: the current resource
>    *
>    * Iterate over all the evictable resources in a resource manager.
>    */
> -#define ttm_resource_manager_for_each_res(man, cursor, res)		\
> -	for (res = ttm_resource_manager_first(man, cursor); res;	\
> +#define ttm_resource_manager_for_each_res(cursor, res)	\
> +	for (res = ttm_resource_manager_first(cursor); res;	\
>   	     res = ttm_resource_manager_next(cursor))
>   
>   struct ttm_kmap_iter *