SLUB: Fix sysfs object handling

SLUB: Fix sysfs object handling

[Christoph Lameter]

If CONFIG_SYSFS is set then free the kmem_cache structure when
sysfs tells us its okay. Otherwise there is the danger (as pointed out by 
Al Viro) that sysfs thinks the kobject still exists after 
kmem_cache_destroy() removed it.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 mm/slub.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2007-12-27 23:03:25.000000000 -0800
+++ linux-2.6/mm/slub.c	2007-12-27 23:03:26.000000000 -0800
@@ -247,7 +247,10 @@ static void sysfs_slab_remove(struct kme
 static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
 static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
 							{ return 0; }
-static inline void sysfs_slab_remove(struct kmem_cache *s) {}
+static inline void sysfs_slab_remove(struct kmem_cache *s)
+{
+	kfree(s);
+}
 #endif
 
 /********************************************************************
@@ -2322,7 +2325,6 @@ void kmem_cache_destroy(struct kmem_cach
 		if (kmem_cache_close(s))
 			WARN_ON(1);
 		sysfs_slab_remove(s);
-		kfree(s);
 	} else
 		up_write(&slub_lock);
 }
@@ -3940,6 +3942,13 @@ static ssize_t slab_attr_store(struct ko
 	return err;
 }
 
+static void kmem_cache_release(struct kobject *kobj)
+{
+	struct kmem_cache *s = to_slab(kobj);
+
+	kfree(s);
+}
+
 static struct sysfs_ops slab_sysfs_ops = {
 	.show = slab_attr_show,
 	.store = slab_attr_store,
@@ -3947,6 +3956,7 @@ static struct sysfs_ops slab_sysfs_ops =
 
 static struct kobj_type slab_ktype = {
 	.sysfs_ops = &slab_sysfs_ops,
+	.release = kmem_cache_release
 };
 
 static int uevent_filter(struct kset *kset, struct kobject *kobj)
@@ -4048,6 +4058,7 @@ static void sysfs_slab_remove(struct kme
 {
 	kobject_uevent(&s->kobj, KOBJ_REMOVE);
 	kobject_del(&s->kobj);
+	kobject_put(&s->kobj);
 }
 
 /*

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Re: SLUB: Fix sysfs object handling

[Andrew Morton]

On Thu, 27 Dec 2007 23:17:13 -0800 (PST) Christoph Lameter <christoph@lameter.com> wrote:

> If CONFIG_SYSFS is set then free the kmem_cache structure when
> sysfs tells us its okay. Otherwise there is the danger (as pointed out by 
> Al Viro) that sysfs thinks the kobject still exists after 
> kmem_cache_destroy() removed it.
> 

Thanks.  I doubt if Al reads linux-mm a lot.  cc added...

> 
> ---
>  mm/slub.c |   15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c	2007-12-27 23:03:25.000000000 -0800
> +++ linux-2.6/mm/slub.c	2007-12-27 23:03:26.000000000 -0800
> @@ -247,7 +247,10 @@ static void sysfs_slab_remove(struct kme
>  static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
>  static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
>  							{ return 0; }
> -static inline void sysfs_slab_remove(struct kmem_cache *s) {}
> +static inline void sysfs_slab_remove(struct kmem_cache *s)
> +{
> +	kfree(s);
> +}
>  #endif
>  
>  /********************************************************************
> @@ -2322,7 +2325,6 @@ void kmem_cache_destroy(struct kmem_cach
>  		if (kmem_cache_close(s))
>  			WARN_ON(1);
>  		sysfs_slab_remove(s);
> -		kfree(s);
>  	} else
>  		up_write(&slub_lock);
>  }
> @@ -3940,6 +3942,13 @@ static ssize_t slab_attr_store(struct ko
>  	return err;
>  }
>  
> +static void kmem_cache_release(struct kobject *kobj)
> +{
> +	struct kmem_cache *s = to_slab(kobj);
> +
> +	kfree(s);
> +}
> +
>  static struct sysfs_ops slab_sysfs_ops = {
>  	.show = slab_attr_show,
>  	.store = slab_attr_store,
> @@ -3947,6 +3956,7 @@ static struct sysfs_ops slab_sysfs_ops =
>  
>  static struct kobj_type slab_ktype = {
>  	.sysfs_ops = &slab_sysfs_ops,
> +	.release = kmem_cache_release
>  };
>  
>  static int uevent_filter(struct kset *kset, struct kobject *kobj)
> @@ -4048,6 +4058,7 @@ static void sysfs_slab_remove(struct kme
>  {
>  	kobject_uevent(&s->kobj, KOBJ_REMOVE);
>  	kobject_del(&s->kobj);
> +	kobject_put(&s->kobj);
>  }
>  
>  /*

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Re: SLUB: Fix sysfs object handling

[Christoph Lameter]

On Fri, 28 Dec 2007, Andrew Morton wrote:

> Thanks.  I doubt if Al reads linux-mm a lot.  cc added...

He already saw the patch. 
http://marc.info/?l=linux-kernel&m=119879781826293&w=2

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