drm/ttm: Move pinned objects off LRU lists when pinning

The ttm_bo_pin() and ttm_bo_unpin() functions weren't moving their
resources off the LRU list to the unevictable list.

Make sure that happens so that pinned objects don't accidently linger
on the LRU lists, and also make sure to move them back once they
are unpinned.

v2:
- Removing from a bulk move must be done with the pin-count still zero.
v3:
- ttm_resource_move_to_lru_tail must be done after pinning with a non-
  NULL resource (Intel CI).
v6:
- Use a TAB instead of space (checkpatch.pl error).

Cc: Christian König <christian.koenig@amd.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: <dri-devel@lists.freedesktop.org>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240911121859.85387-3-thomas.hellstrom@linux.intel.com

drivers/gpu/drm/ttm/ttm_bo.c

@@ -594,7 +594,8 @@ void ttm_bo_pin(struct ttm_buffer_object *bo)
 	spin_lock(&bo->bdev->lru_lock);
 	if (bo->resource)
 		ttm_resource_del_bulk_move(bo->resource, bo);
-	++bo->pin_count;
+	if (!bo->pin_count++ && bo->resource)
+		ttm_resource_move_to_lru_tail(bo->resource);
 	spin_unlock(&bo->bdev->lru_lock);
 }
 EXPORT_SYMBOL(ttm_bo_pin);
@@ -613,9 +614,10 @@ void ttm_bo_unpin(struct ttm_buffer_object *bo)
 		return;
 
 	spin_lock(&bo->bdev->lru_lock);
-	--bo->pin_count;
-	if (bo->resource)
+	if (!--bo->pin_count && bo->resource) {
 		ttm_resource_add_bulk_move(bo->resource, bo);
+		ttm_resource_move_to_lru_tail(bo->resource);
+	}
 	spin_unlock(&bo->bdev->lru_lock);
 }
 EXPORT_SYMBOL(ttm_bo_unpin);