kref: add kref_set()

This adds kref_set() to the kref api for future use by people who really
know what they are doing with krefs...

From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/kref.h

@@ -24,6 +24,7 @@ struct kref {
 	atomic_t refcount;
 };
 
+void kref_set(struct kref *kref, int num);
 void kref_init(struct kref *kref);
 void kref_get(struct kref *kref);
 int kref_put(struct kref *kref, void (*release) (struct kref *kref));

lib/kref.c

@@ -14,14 +14,24 @@
 #include <linux/kref.h>
 #include <linux/module.h>
 
+/**
+ * kref_set - initialize object and set refcount to requested number.
+ * @kref: object in question.
+ * @num: initial reference counter
+ */
+void kref_set(struct kref *kref, int num)
+{
+	atomic_set(&kref->refcount, num);
+	smp_mb();
+}
+
 /**
  * kref_init - initialize object.
  * @kref: object in question.
  */
 void kref_init(struct kref *kref)
 {
-	atomic_set(&kref->refcount,1);
+	kref_set(kref, 1);
-	smp_mb();
 }
 
 /**
@@ -61,6 +71,7 @@ int kref_put(struct kref *kref, void (*release)(struct kref *kref))
 	return 0;
 }
 
+EXPORT_SYMBOL(kref_set);
 EXPORT_SYMBOL(kref_init);
 EXPORT_SYMBOL(kref_get);
 EXPORT_SYMBOL(kref_put);