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Message-Id: <1244681467.8361.654.camel@yhuang-dev.sh.intel.com>
Date: Thu, 11 Jun 2009 08:51:07 +0800
From: Huang Ying <ying.huang@...el.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...e.hu>,
Andrew Morton <akpm@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Theodore Tso <tytso@....edu>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Mathieu Desnoyers <compudj@...stal.dyndns.org>,
Lai Jiangshan <laijs@...fujitsu.com>,
"Martin J. Bligh" <mbligh@...igh.org>,
Christoph Hellwig <hch@...radead.org>,
Li Zefan <lizf@...fujitsu.com>,
"H. Peter Anvin" <hpa@...or.com>,
Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
Masami Hiramatsu <mhiramat@...hat.com>
Subject: Re: [PATCH 3/3] ring-buffer: add design document
On Thu, 2009-06-11 at 03:53 +0800, Steven Rostedt wrote:
> +
> +cmpxchg - hardware assisted atomic transaction that performs the following:
> +
> + A = B iff previous A == C
> +
> + R = cmpxchg(A, C, B) is saying that we replace A with B if and only if
> + current A is equal to C, and we put the old (current) A into R
> +
> + R gets the previous A regardless if A is updated with B or not.
> +
> + To see if the update was successful a compare of R == C may be used.
As far as I know, some architectures have no hardware assisted (NMI
safe) cmpxchg. Is it OK to use cmpxchg in architecture-independent code?
Best Regards,
Huang Ying
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