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Message-ID: <alpine.LFD.0.999.0708180709060.3666@enigma.security.iitk.ac.in>
Date: Sat, 18 Aug 2007 07:11:01 +0530 (IST)
From: Satyam Sharma <satyam@...radead.org>
To: Christoph Lameter <clameter@....com>
cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Nick Piggin <nickpiggin@...oo.com.au>,
Paul Mackerras <paulus@...ba.org>,
Segher Boessenkool <segher@...nel.crashing.org>,
heiko.carstens@...ibm.com, horms@...ge.net.au,
linux-kernel@...r.kernel.org, rpjday@...dspring.com, ak@...e.de,
netdev@...r.kernel.org, cfriesen@...tel.com,
akpm@...ux-foundation.org, jesper.juhl@...il.com,
linux-arch@...r.kernel.org, zlynx@....org, schwidefsky@...ibm.com,
Chris Snook <csnook@...hat.com>, davem@...emloft.net,
wensong@...ux-vs.org, wjiang@...ilience.com
Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all
architectures
On Fri, 17 Aug 2007, Christoph Lameter wrote:
> On Fri, 17 Aug 2007, Paul E. McKenney wrote:
>
> > On Sat, Aug 18, 2007 at 08:09:13AM +0800, Herbert Xu wrote:
> > > On Fri, Aug 17, 2007 at 04:59:12PM -0700, Paul E. McKenney wrote:
> > > >
> > > > gcc bugzilla bug #33102, for whatever that ends up being worth. ;-)
> > >
> > > I had totally forgotten that I'd already filed that bug more
> > > than six years ago until they just closed yours as a duplicate
> > > of mine :)
> > >
> > > Good luck in getting it fixed!
> >
> > Well, just got done re-opening it for the third time. And a local
> > gcc community member advised me not to give up too easily. But I
> > must admit that I am impressed with the speed that it was identified
> > as duplicate.
> >
> > Should be entertaining! ;-)
>
> Right. ROTFL... volatile actually breaks atomic_t instead of making it
> safe. x++ becomes a register load, increment and a register store. Without
> volatile we can increment the memory directly.
No code does (or would do, or should do):
x.counter++;
on an "atomic_t x;" anyway.
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