linux-kernel - [PATCH] kref: remove kref

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Date:	Tue, 16 Mar 2010 15:14:51 +1100
From:	NeilBrown <neilb@...e.de>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] 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@...e.de>
--

The two 'kref_init' calls in ima_iint.c could equally be a single
call after the kmem_cache_alloc in ima_inode_alloc, but this version
was the minimal code change.


diff --git a/include/linux/kref.h b/include/linux/kref.h
index b0cb0eb..13003ee 100644
--- a/include/linux/kref.h
+++ b/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));
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 076c7c8..b2d70d3 100644
--- a/kernel/user_namespace.c
+++ b/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;
 }
diff --git a/lib/kref.c b/lib/kref.c
index 9ecd6e8..69761d3 100644
--- a/lib/kref.c
+++ b/lib/kref.c
@@ -15,23 +15,13 @@
 #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)
 {
-	kref_set(kref, 1);
+	atomic_set(&kref->refcount, 1);
+	smp_mb();
 }
 
 /**
@@ -71,7 +61,6 @@ 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);
diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
index 2d4d05d..91c31d8 100644
--- a/security/integrity/ima/ima_iint.c
+++ b/security/integrity/ima/ima_iint.c
@@ -93,7 +93,7 @@ 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);
 }
 
@@ -132,7 +132,7 @@ 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)
--
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