kref: remove kref_set

Of the three uses of kref_set in the kernel:

 One really should be kref_put as the code is letting go of a
    reference,
 Two really should be kref_init because the kref is being
    initialised.

This suggests that making kref_set available encourages bad code.
So fix the three uses and remove kref_set completely.

Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/kref.h

@@ -21,7 +21,6 @@ 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));

kernel/user_namespace.c

@@ -54,8 +54,8 @@ int create_user_ns(struct cred *new)
 #endif
 	/* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
 
-	/* alloc_uid() incremented the userns refcount.  Just set it to 1 */
-	kref_set(&ns->kref, 1);
+	/* root_user holds a reference to ns, our reference can be dropped */
+	put_user_ns(ns);
 
 	return 0;
 }

lib/kref.c

@@ -15,24 +15,14 @@
 #include <linux/module.h>
 #include <linux/slab.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)
 {
-	kref_set(kref, 1);
+	atomic_set(&kref->refcount, 1);
+	smp_mb();
 }
 
 /**
@@ -72,7 +62,6 @@ 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);

security/integrity/ima/ima_iint.c

@@ -94,7 +94,7 @@ void iint_free(struct kref *kref)
 		       iint->opencount);
 		iint->opencount = 0;
 	}
-	kref_set(&iint->refcount, 1);
+	kref_init(&iint->refcount);
 	kmem_cache_free(iint_cache, iint);
 }
 
@@ -133,7 +133,7 @@ static void init_once(void *foo)
 	iint->readcount = 0;
 	iint->writecount = 0;
 	iint->opencount = 0;
-	kref_set(&iint->refcount, 1);
+	kref_init(&iint->refcount);
 }
 
 static int __init ima_iintcache_init(void)