diff --git a/include/linux/idr.h b/include/linux/idr.h
index 0edda41..9a2d762 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -14,6 +14,7 @@
 
 #include <linux/types.h>
 #include <linux/bitops.h>
+#include <linux/init.h>
 
 #if BITS_PER_LONG == 32
 # define IDR_BITS 5
@@ -115,4 +116,6 @@
 void ida_destroy(struct ida *ida);
 void ida_init(struct ida *ida);
 
+void __init idr_init_cache(void);
+
 #endif /* __IDR_H__ */