linux-kernel - Re: [PATCH 1/1] x86: Convert cpuinfo_x86 array to a per

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Message-ID: <20070925003127.GQ11455@redhat.com>
Date:	Mon, 24 Sep 2007 20:31:27 -0400
From:	Dave Jones <davej@...hat.com>
To:	roel <12o3l@...cali.nl>
Cc:	travis@....com, Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@...e.de>, Christoph Lameter <clameter@....com>,
	Jack Steiner <steiner@....com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] x86: Convert cpuinfo_x86 array to a per_cpu array
	v3

On Tue, Sep 25, 2007 at 02:20:01AM +0200, roel wrote:
 
 > >  > >  	if ((c->x86_vendor != X86_VENDOR_AMD) || (c->x86 != 5) ||
 > >  > >  		((c->x86_model != 12) && (c->x86_model != 13)))
 > >  > 
 > >  > while we're at it, we could change this to
 > >  > 
 > >  >   	if (!(c->x86_vendor == X86_VENDOR_AMD && c->x86 == 5 &&
 > >  >   		(c->x86_model == 12 || c->x86_model == 13)))
 > > 
 > > For what purpose?  There's nothing wrong with the code as it stands,
 > > and inverting the tests means we'd have to move a bunch of
 > > code inside the if arm instead of just returning -ENODEV.
 > 
 > It's not inverting the test, so you don't need to move code. It evaluates 
 > the same, only the combined negation is moved to the front. I suggested it
 > to increase clarity, it results in the same assembly language.

I don't see it as being particularly more readable after this change.
In fact, the reverse, as my previous comment implied, I missed the
initial !
Given this code works fine, and there's no discernable gain from
changing it, I'm not particularly enthusiastic about this modification.

	Dave

-- 
http://www.codemonkey.org.uk
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