diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index e4c2143..ed73ce5 100644
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -368,6 +368,7 @@
 
 	/* Device state and target state. */
 	int state, target;
+	struct mutex state_mutex;
 	int stopped;		/* device (ccw_device_start) was stopped */
 
 	/* reference count. */