linux-kernel - Re: kfree(0)

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Message-Id: <1187132149.2618.2.camel@laptopd505.fenrus.org>
Date:	Tue, 14 Aug 2007 15:55:48 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Tim Bird <tim.bird@...sony.com>
Cc:	linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: kfree(0) - ok?


On Tue, 2007-08-14 at 15:59 -0700, Tim Bird wrote:
> Hi all,
> 
> I have a quick question.
> 
> I'm trying to resurrect a patch from the Linux-tiny patch suite,
> to do accounting of kmalloc memory allocations.  In testing it
> with Linux 2.6.22, I've found a large number of kfrees of
> NULL pointers.
> 
> Is this considered OK?  Or should I examine the offenders
> to see if something is coded badly?

kfree(NULL) is explicitly ok and it saves code size to not check
anywhere
(the idea is that kfree(kmalloc(...)); is a guaranteed safe nop)

NULL is not 0 though.


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