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Message-Id: <200708241350.45061.vda.linux@googlemail.com>
Date: Fri, 24 Aug 2007 13:50:44 +0100
From: Denys Vlasenko <vda.linux@...glemail.com>
To: Paul Mackerras <paulus@...ba.org>
Cc: Satyam Sharma <satyam@...radead.org>,
Stefan Richter <stefanr@...6.in-berlin.de>,
Christoph Lameter <clameter@....com>,
Chris Snook <csnook@...hat.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-arch@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
netdev@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
ak@...e.de, heiko.carstens@...ibm.com, davem@...emloft.net,
schwidefsky@...ibm.com, wensong@...ux-vs.org, horms@...ge.net.au,
wjiang@...ilience.com, cfriesen@...tel.com, zlynx@....org,
rpjday@...dspring.com, jesper.juhl@...il.com,
segher@...nel.crashing.org,
Herbert Xu <herbert@...dor.apana.org.au>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures
On Thursday 16 August 2007 00:22, Paul Mackerras wrote:
> Satyam Sharma writes:
> In the kernel we use atomic variables in precisely those situations
> where a variable is potentially accessed concurrently by multiple
> CPUs, and where each CPU needs to see updates done by other CPUs in a
> timely fashion. That is what they are for. Therefore the compiler
> must not cache values of atomic variables in registers; each
> atomic_read must result in a load and each atomic_set must result in a
> store. Anything else will just lead to subtle bugs.
Amen.
--
vda
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