diff --git a/arch/s390/include/asm/ccwgroup.h b/arch/s390/include/asm/ccwgroup.h
index ebc2913f9ee0..057ce0ca6377 100644
--- a/arch/s390/include/asm/ccwgroup.h
+++ b/arch/s390/include/asm/ccwgroup.h
@@ -10,6 +10,8 @@ struct ccw_driver;
  * @count: number of attached slave devices
  * @dev: embedded device structure
  * @cdev: variable number of slave devices, allocated as needed
+ * @ungroup_work: work to be done when a ccwgroup notifier has action
+ *	type %BUS_NOTIFY_UNBIND_DRIVER
  */
 struct ccwgroup_device {
 	enum {