Re: [PATCH] drm: Handle unexpected holes in color-eviction

Quoting Chris Wilson (2018-02-19 13:35:43)

+++ b/drivers/gpu/drm/drm_mm.c @@ -836,9 +836,24 @@ struct drm_mm_node *drm_mm_scan_color_evict(struct drm_mm_scan *scan) if (!mm->color_adjust) return NULL;

•   hole = list_first_entry(&mm->hole_stack, typeof(*hole), hole_stack);
  

•   hole_start = __drm_mm_hole_node_start(hole);
  

•   hole_end = hole_start + hole->hole_size;
  

•   /*
  

•    * The hole found during scanning should ideally be the first element
  

•    * in the hole_stack list, but due to side-effects in the driver it
  

•    * may not be.
  

•    */
  

•   list_for_each_entry(hole, &mm->hole_stack, hole_stack) {
  

•           hole_start = __drm_mm_hole_node_start(hole);
  

•           hole_end = hole_start + hole->hole_size;
  

•           if (hole_start <= scan->hit_start &&
  

•               hole_end >= scan->hit_end)
  

How about some likely() here?

•                   break;
  

•   }
  

•   /* We should only be called after we found the hole previously */
  

•   DRM_MM_BUG_ON(&hole->hole_stack == &mm->hole_stack);
  

•   if (unlikely(&hole->hole_stack == &mm->hole_stack))
  

Would be more readable as:

if (...) { DRM_MM_BUG() }

Reviewed-by: Joonas Lahtinen joonas.lahtinen@linux.intel.com

Regards, Joonas