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Date: Fri, 17 Aug 2007 12:16:39 +1000
From: Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all
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To: Christoph Lameter <clameter@sgi.com>
Cc: Chris Snook <csnook@redhat.com>, =?ISO-8859-1?Q?Ilpo_J=E4rvinen?= <ilpo.jarvinen@helsinki.fi>, Herbert Xu <herbert@gondor.apana.org.au>, Satyam Sharma <satyam@infradead.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Stefan Richter <stefanr@s5r6.in-berlin.de>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-arch@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org>, Netdev <netdev@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, ak@suse.de, heiko.carstens@de.ibm.com, David Miller <davem@davemloft.net>, schwidefsky@de.ibm.com, wensong@linux-vs.org, horms@verge.net.au, wjiang@resilience.com, cfriesen@nortel.com, zlynx@acm.org, rpjday@mindspring.com, jesper.juhl@gmail.com, segher@kernel.crashing.org
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Christoph Lameter writes:

> No it does not have any volatile semantics. atomic_dec() can be reordered 
> at will by the compiler within the current basic unit if you do not add a 
> barrier.

Volatile doesn't mean it can't be reordered; volatile means the
accesses can't be eliminated.

Paul.