From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932346Ab2HFQtG (ORCPT <rfc822;w@1wt.eu>);
	Mon, 6 Aug 2012 12:49:06 -0400
Received: from mail-qc0-f174.google.com ([209.85.216.174]:48523 "EHLO
	mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S932271Ab2HFQtE (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 6 Aug 2012 12:49:04 -0400
MIME-Version: 1.0
In-Reply-To: <1344266096.2486.17.camel@lorien2>
References: <1342221125.17464.8.camel@lorien2>
	<CAOJsxLGjnMxs9qERG5nCfGfcS3jy6Rr54Ac36WgVnOtP_pDYgQ@mail.gmail.com>
	<1344224494.3053.5.camel@lorien2>
	<1344266096.2486.17.camel@lorien2>
Date: Tue, 7 Aug 2012 01:49:03 +0900
Message-ID: <CAAmzW4Ne5pD90r+6zrrD-BXsjtf5OqaKdWY+2NSGOh1M_sWq4g@mail.gmail.com>
Subject: Re: [PATCH RESEND] mm: Restructure kmem_cache_create() to move debug
 cache integrity checks into a new function
From: JoonSoo Kim <js1304@gmail.com>
To: shuah.khan@hp.com
Cc: Pekka Enberg <penberg@kernel.org>, cl@linux.com, glommer@parallels.com,
        linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        David Rientjes <rientjes@google.com>, shuahkhan@gmail.com
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> 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.