linux-kernel - Re: [PATCH] lib/idr.c: Zero memory properly in idr_remove

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Date:	Wed, 14 Jan 2009 09:19:01 +0200
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	"Andrew Morton" <akpm@...ux-foundation.org>
Cc:	"Manfred Spraul" <manfred@...orfullife.com>, krh@...hat.com,
	stefanr@...6.in-berlin.de, dcm@....org, Nadia.Derbey@...l.net,
	linux1394-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, paulmck@...ibm.com
Subject: Re: [PATCH] lib/idr.c: Zero memory properly in idr_remove_all

On Wed, Jan 14, 2009 at 12:48 AM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
>> If the idr code passes uninitialized objects to kmem_cache_free(), then
>> the next kmem_cache_alloc will return a bad object.
>>
>
> None of this got us much closer to fixing the bug ;)
>
> What do we think of just removing the constructor and using
> kmem_cache_zalloc()?

Why do I get the feeling that we have merged a similar patch before?

Acked-by: Pekka Enberg <penberg@...helsinki.fi>

>
> --- a/lib/idr.c~a
> +++ a/lib/idr.c
> @@ -121,7 +121,7 @@ int idr_pre_get(struct idr *idp, gfp_t g
>  {
>        while (idp->id_free_cnt < IDR_FREE_MAX) {
>                struct idr_layer *new;
> -               new = kmem_cache_alloc(idr_layer_cache, gfp_mask);
> +               new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
>                if (new == NULL)
>                        return (0);
>                move_to_free_list(idp, new);
> @@ -623,16 +623,10 @@ void *idr_replace(struct idr *idp, void
>  }
>  EXPORT_SYMBOL(idr_replace);
>
> -static void idr_cache_ctor(void *idr_layer)
> -{
> -       memset(idr_layer, 0, sizeof(struct idr_layer));
> -}
> -
>  void __init idr_init_cache(void)
>  {
>        idr_layer_cache = kmem_cache_create("idr_layer_cache",
> -                               sizeof(struct idr_layer), 0, SLAB_PANIC,
> -                               idr_cache_ctor);
> +                               sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
>  }
>
>  /**
> _
>
> --
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