diff --git a/include/linux/kref.h b/include/linux/kref.h
index 6cc38fc..d4a62ab 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -24,5 +24,7 @@
 void kref_init(struct kref *kref);
 void kref_get(struct kref *kref);
 int kref_put(struct kref *kref, void (*release) (struct kref *kref));
+int kref_sub(struct kref *kref, unsigned int count,
+	     void (*release) (struct kref *kref));
 
 #endif /* _KREF_H_ */