[PATCH 1/3] drm/ttm: fix ttm_bo_bulk_move_helper

[Michel Dänzer]

On 2018-08-31 3:10 p.m., Christian König wrote:
> Staring at the function for six hours, just to essentially move one line
> of code.

That sucks, but the commit log should describe what the problem was and
how this patch solves it.


> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/ttm/ttm_bo.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 35d53d81f486..138c98902033 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -250,15 +250,18 @@ EXPORT_SYMBOL(ttm_bo_move_to_lru_tail);
>  static void ttm_bo_bulk_move_helper(struct ttm_lru_bulk_move_pos *pos,
>  				    struct list_head *lru, bool is_swap)
>  {
> +	struct list_head *list;
>  	LIST_HEAD(entries);
>  	LIST_HEAD(before);
> -	struct list_head *list1, *list2;
>  
> -	list1 = is_swap ? &pos->last->swap : &pos->last->lru;
> -	list2 = is_swap ? pos->first->swap.prev : pos->first->lru.prev;
> +	reservation_object_assert_held(pos->last->resv);
> +	list = is_swap ? &pos->last->swap : &pos->last->lru;
> +	list_cut_position(&entries, lru, list);
> +
> +	reservation_object_assert_held(pos->first->resv);
> +	list = is_swap ? pos->first->swap.prev : pos->first->lru.prev;
> +	list_cut_position(&before, &entries, list);

So the problem was that the first list_cut_position call could result in
list2 pointing to la-la-land? Good catch!


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer