linux-kernel - Re: [patch 1/5]thp: improve the error code path

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Message-ID: <20111110141412.GW5075@redhat.com>
Date:	Thu, 10 Nov 2011 15:14:12 +0100
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Shaohua Li <shaohua.li@...el.com>
Cc:	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [patch 1/5]thp: improve the error code path

On Thu, Nov 10, 2011 at 01:56:49PM +0800, Shaohua Li wrote:
> +static struct kobject *hugepage_kobj;

It's minor nitpick but we don't need to put this in .bss, passing it
as hugepage_init_sysfs(struct kobject **hugepage_kobj) and storing it
there in case the error returned by hugepage_init_sysfs is zero should
be fine. The feature cannot be unloaded so we can lose the pointer
after init is complete.

Then I think we can be done with this... and it looks better now.

> +static int __init hugepage_init_sysfs(void)
>  {
>  	int err;
> -#ifdef CONFIG_SYSFS
> -	static struct kobject *hugepage_kobj;
> -#endif
>  
> -	err = -EINVAL;
> -	if (!has_transparent_hugepage()) {
> -		transparent_hugepage_flags = 0;
> -		goto out;
> -	}
> -
> -#ifdef CONFIG_SYSFS
> -	err = -ENOMEM;
>  	hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
>  	if (unlikely(!hugepage_kobj)) {
>  		printk(KERN_ERR "hugepage: failed kobject create\n");
> -		goto out;
> +		return -ENOMEM;
>  	}
>  
>  	err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group);
>  	if (err) {
>  		printk(KERN_ERR "hugepage: failed register hugeage group\n");
> -		goto out;
> +		goto delete_obj;
>  	}
>  
>  	err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group);
>  	if (err) {
>  		printk(KERN_ERR "hugepage: failed register hugeage group\n");
> -		goto out;
> +		goto remove_hp_group;
>  	}
> -#endif
> +
> +	return 0;
> +
> +remove_hp_group:
> +	sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
> +delete_obj:
> +	kobject_put(hugepage_kobj);
> +	return err;
> +}
> +
> +static void __init hugepage_exit_sysfs(void)
> +{
> +	sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
> +	sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
> +	kobject_put(hugepage_kobj);
> +}
> +#else
> +static inline int hugepage_init_sysfs(void)
> +{
> +	return 0;
> +}
> +
> +static inline void hugepage_exit_sysfs(void)
> +{
> +}
> +#endif /* CONFIG_SYSFS */
> +
> +static int __init hugepage_init(void)
> +{
> +	int err;

  	struct kobject *hugepage_kobj;

> +
> +	if (!has_transparent_hugepage()) {
> +		transparent_hugepage_flags = 0;
> +		return -EINVAL;
> +	}
> +
> +	err = hugepage_init_sysfs();

	err = hugepage_init_sysfs(&hugepage_kobj);


> +	if (err)
> +		return err;
>  
>  	err = khugepaged_slab_init();
>  	if (err)
> @@ -545,7 +572,9 @@ static int __init hugepage_init(void)
>  
>  	set_recommended_min_free_kbytes();
>  
> +	return 0;
>  out:
> +	hugepage_exit_sysfs();

	hugepage_exit_sysfs(hugepage_kobj);

>  	return err;
>  }
>  module_init(hugepage_init)
> 
> 
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