Hello Thomas Hellström,
Commit bb8aa27eff6f ("drm/ttm, drm_xe, Implement
ttm_lru_walk_for_evict() using the guarded LRU iteration") from Jun
23, 2025 (linux-next), leads to the following Smatch static checker
warning:
drivers/gpu/drm/ttm/ttm_bo_util.c:899 ttm_lru_walk_for_evict()
warn: 'bo' isn't an ERR_PTR
drivers/gpu/drm/ttm/ttm_bo_util.c
883 s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device
*bdev,
884 struct ttm_resource_manager *man, s64 target)
885 {
886 struct ttm_bo_lru_cursor cursor;
887 struct ttm_buffer_object *bo;
888 s64 progress = 0;
889 s64 lret;
890
891 ttm_bo_lru_for_each_reserved_guarded(&cursor, man, &walk->arg,
bo) {
892 lret = walk->ops->process_bo(walk, bo);
893 if (lret == -EBUSY || lret == -EALREADY)
894 lret = 0;
895 progress = (lret < 0) ? lret : progress + lret;
896 if (progress < 0 || progress >= target)
897 break;
898 }
899 if (IS_ERR(bo))
900 return PTR_ERR(bo);
The ttm_bo_lru_for_each_reserved_guarded() macro checks for IS_ERR_OR_NULL()
but it can only be NULL. These things are a bit frustrating to me because
when a function returns both error pointers and NULL then ideally there is a
reason for that and it should be documented. "This function returns error
pointers if there is an error (kmalloc failed etc) or NULL if the object is
not found".
https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/
901
902 return progress;
It's strange to me that we returns progress values which are greater than the
target value.
903 }
regards,
dan carpenter
