linux-kernel - Re: [PATCH RESEND] mm: Restructure kmem_cache_create() to move debug cache integrity checks into a new function

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Date:	Tue, 7 Aug 2012 01:49:03 +0900
From:	JoonSoo Kim <js1304@...il.com>
To:	shuah.khan@...com
Cc:	Pekka Enberg <penberg@...nel.org>, cl@...ux.com,
	glommer@...allels.com, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>, shuahkhan@...il.com
Subject: Re: [PATCH RESEND] mm: Restructure kmem_cache_create() to move debug
 cache integrity checks into a new function

> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 12637ce..08bc2a4 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -23,6 +23,41 @@ enum slab_state slab_state;
>  LIST_HEAD(slab_caches);
>  DEFINE_MUTEX(slab_mutex);
>
> +static int kmem_cache_sanity_check(const char *name, size_t size)
> +{
> +#ifdef CONFIG_DEBUG_VM
> +       struct kmem_cache *s = NULL;
> +
> +       list_for_each_entry(s, &slab_caches, list) {
> +               char tmp;
> +               int res;
> +
> +               /*
> +                * This happens when the module gets unloaded and doesn't
> +                * destroy its slab cache and no-one else reuses the vmalloc
> +                * area of the module.  Print a warning.
> +                */
> +               res = probe_kernel_address(s->name, tmp);
> +               if (res) {
> +                       pr_err("Slab cache with size %d has lost its name\n",
> +                              s->object_size);
> +                       continue;
> +               }
> +
> +               if (!strcmp(s->name, name)) {
> +                       pr_err("%s (%s): Cache name already exists.\n",
> +                              __func__, name);
> +                       dump_stack();
> +                       s = NULL;
> +                       return -EINVAL;
> +               }
> +       }
> +
> +       WARN_ON(strchr(name, ' '));     /* It confuses parsers */
> +#endif
> +       return 0;
> +}

As I know, following is more preferable than above.

#ifdef CONFIG_DEBUG_VM
static int kmem_cache_sanity_check(const char *name, size_t size);
#else
static inline int kmem_cache_sanity_check(const char *name, size_t size)
{
return 0;
}
#endif

Is there any reason to do like that?
Thanks.
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