linux-kernel - Re: [PATCH] slab: deal with NULL pointers passed to kmem_cache

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Message-ID: <84144f020703210513i37d1576erb7814483bcaad505@mail.gmail.com>
Date:	Wed, 21 Mar 2007 14:13:52 +0200
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	"Jarek Poplawski" <jarkao2@...pl>
Cc:	"Eric Dumazet" <dada1@...mosbay.com>,
	"Andrew Morton" <akpm@...ux-foundation.org>, mpm@...enic.com,
	"Christoph Lameter" <clameter@....com>,
	"ast@...dv.de" <ast@...dv.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] slab: deal with NULL pointers passed to kmem_cache_free

On 3/21/07, Jarek Poplawski <jarkao2@...pl> wrote:
> I think Pekka was right (it looks he changed his mind now) something
> should be done here. I think something like this should be a minimum:
>
> BUG_ON(!objp || virt_to_cache(objp) != cachep);
>
> to show distinctly what's going on.

No, if we were to add a NULL check in kmem_cache_free(), it should
behave like kfree() does. Anyway, if you feel about this strongly I
suspect the best solution is to add a __kmem_cache_free which does
_not_ have the NULL check and convert those super-hot paths to use it.
Sort of what Andrew suggested already.
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