linux-kernel - Re: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers

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Date:	Wed, 10 Sep 2014 17:28:11 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Dan Carpenter <dan.carpenter@...cle.com>
cc:	Theodore Ts'o <tytso@....edu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers

On Wed, 10 Sep 2014, Dan Carpenter wrote:

> > BTW if we stretch this argument a little bit more, we should also kill the 
> > ZERO_OR_NULL_PTR() check from kfree() and make it callers responsibility 
> > to perform the checking only if applicable ... we are currently doing a 
> > lot of pointless checking in cases where caller would be able to guarantee 
> > that the pointer is going to be non-NULL.
> 
> What you're saying is that we should remove the ZERO_SIZE_PTR
> completely.  ZERO_SIZE_PTR is a very useful idiom and also it's too late
> to remove it because everything depends on it.

I was just argumenting that if we care about single additional test in 
this path, the ZERO_OR_NULL_PTR() should have never been added at the 
first place, and the responsibility for checking should have been kept at 
callers.

Too late for this now, yes.

-- 
Jiri Kosina
SUSE Labs
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