--- zzzz-none-000/linux-2.6.39.4/include/linux/kref.h	2011-08-03 19:43:28.000000000 +0000
+++ puma6-arm-6490-729/linux-2.6.39.4/include/linux/kref.h	2021-11-10 13:23:10.000000000 +0000
@@ -16,6 +16,7 @@
 #define _KREF_H_
 
 #include <linux/types.h>
+#include <linux/atomic.h>
 
 struct kref {
 	atomic_t refcount;
@@ -27,4 +28,8 @@
 int kref_sub(struct kref *kref, unsigned int count,
 	     void (*release) (struct kref *kref));
 
+static inline int __must_check kref_get_unless_zero(struct kref *kref)
+{
+	return atomic_add_unless(&kref->refcount, 1, 0);
+}
 #endif /* _KREF_H_ */