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

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Message-ID: <1344272614.2486.40.camel@lorien2>
Date:	Mon, 06 Aug 2012 11:03:34 -0600
From:	Shuah Khan <shuah.khan@...com>
To:	JoonSoo Kim <js1304@...il.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

On Tue, 2012-08-07 at 01:49 +0900, JoonSoo Kim wrote:
> > 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.

No reason, just something I am used to doing :) inline is a good idea. I
can fix that easily and send v2 patch.

-- Shuah


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