linux-kernel - Re: [PATCH 13/16] percpu: remove per_cpu_

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Message-ID: <4AD6E3EC.8080901@kernel.org>
Date:	Thu, 15 Oct 2009 17:57:16 +0900
From:	Tejun Heo <tj@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	"Luck, Tony" <tony.luck@...el.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"rusty@...tcorp.com.au" <rusty@...tcorp.com.au>,
	"mingo@...hat.com" <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"cebbert@...hat.com" <cebbert@...hat.com>
Subject: Re: [PATCH 13/16] percpu: remove per_cpu__ prefix.

Hello,

H. Peter Anvin wrote:
> Okay... I also don't seem to understand the more fundamental issue here,
> which is:
> 
> Why are we dropping the prefix?
> 
> It may be "insufficient", but at least it stands out like a sore thumb
> and makes mistakes harder.  It would be a different thing if we could
> actually use the TLS ABI, but we really can't.

The reason for actively removing the prefix is because it forces us to
have two different accessors for static and dynamic ones which is made
worse by any accessor which will accept dynamic ones will accept
anything (static ones enclosed by per_cpu_var(), dynamic ones, plain
wrong random value).  Also, wide spread use of per_cpu_var() in
generic code will basically circumvent any meaningful protection the
prefix provided.

Thanks.

-- 
tejun
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