linux-kernel - Re: [block IO crash] Re: 2.6.39-rc5-git2 boot crashs

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Date:	Wed, 4 May 2011 12:38:28 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Pekka Enberg <penberg@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tejun Heo <tj@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	Jens Axboe <axboe@...nel.dk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	werner <w.landgraf@...ru>, "H. Peter Anvin" <hpa@...or.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [block IO crash] Re: 2.6.39-rc5-git2 boot crashs

On Wed, May 4, 2011 at 12:30 PM, Christoph Lameter <cl@...ux.com> wrote:
>
> The naming convention came about from the existing this_cpu_xxx
> operations

You're missing my point.

An "add" operation makes sense even if it isn't atomic, because
atomicity isn't a part of the definition of "add".

But cmpxchg DOES NOT MAKE SENSE without atomicity guarantees.

The whole operation is about atomicity.

Having a version that isn't atomic is STUPID. It's misleading. It's _wrong_.

In contrast, having a non-atomic "add" version is understandable.

So when  you say "naming convention", you're missing the much bigger
naming convention. Namely the "cmpxchg" part!

                           Linus
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