Re: [RFC] SL[AUO]B common code 8/9] slabs: list addition move to slab_common

Glauber Costa
2012-05-16T10:11:12Z

On 05/15/2012 12:15 AM, Christoph Lameter wrote:
> Move the code to append the new kmem_cache to the list of slab caches to
> the kmem_cache_create code in the shared code.
>
> This is possible now since the acquisition of the mutex was moved into
> kmem_cache_create().
>
> Signed-off-by: Christoph Lameter<cl@linux.com>
>
>
> ---
> mm/slab.c | 7 +++++--
> mm/slab_common.c | 3 +++
> mm/slub.c | 2 --
> 3 files changed, 8 insertions(+), 4 deletions(-)
>
> Index: linux-2.6/mm/slab_common.c
> ===================================================================
> --- linux-2.6.orig/mm/slab_common.c 2012-05-14 08:39:27.859145830 -0500
> +++ linux-2.6/mm/slab_common.c 2012-05-14 08:39:29.827145790 -0500
> @@ -98,6 +98,9 @@ struct kmem_cache *kmem_cache_create(con
>
> s = __kmem_cache_create(name, size, align, flags, ctor);
>
> + if (s&& s->refcount == 1)
> + list_add(&s->list,&slab_caches);
> +
> oops:

I personally think that the refcount == 1 test is too fragile.
It happens to be true, and is likely to be true in the future, but there
is no particular reason that is *has* to be true forever.

Also, the only reasons it exists, seems to be to go around the fact that
the slab already adds the kmalloc caches to a list in a slightly
different way. And there has to be cleaner ways to achieve that.