drm/ttm: add optional LRU removal callback v2

Useful for driver specific LRU handling.

v2: fix typo in comment
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_bo.c

@@ -186,8 +186,12 @@ EXPORT_SYMBOL(ttm_bo_add_to_lru);
 
 int ttm_bo_del_from_lru(struct ttm_buffer_object *bo)
 {
+	struct ttm_bo_device *bdev = bo->bdev;
 	int put_count = 0;
 
+	if (bdev->driver->lru_removal)
+		bdev->driver->lru_removal(bo);
+
 	if (!list_empty(&bo->swap)) {
 		list_del_init(&bo->swap);
 		++put_count;
@@ -197,11 +201,6 @@ int ttm_bo_del_from_lru(struct ttm_buffer_object *bo)
 		++put_count;
 	}
 
-	/*
-	 * TODO: Add a driver hook to delete from
-	 * driver-specific LRU's here.
-	 */
-
 	return put_count;
 }
 
@@ -235,6 +234,9 @@ void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo)
 
 	lockdep_assert_held(&bo->resv->lock.base);
 
+	if (bdev->driver->lru_removal)
+		bdev->driver->lru_removal(bo);
+
 	if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
 		list_del_init(&bo->swap);
 		list_del_init(&bo->lru);

include/drm/ttm/ttm_bo_driver.h

@@ -434,6 +434,12 @@ struct ttm_bo_driver {
 	 */
 	int (*io_mem_reserve)(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem);
 	void (*io_mem_free)(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem);
+
+	/**
+	 * Optional driver callback for when BO is removed from the LRU.
+	 * Called with LRU lock held immediately before the removal.
+	 */
+	void (*lru_removal)(struct ttm_buffer_object *bo);
 };
 
 /**