From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Chris Snook <csnook@redhat.com>,
dhowells@redhat.com, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, torvalds@linux-foundation.org,
netdev@vger.kernel.org, akpm@linux-foundation.org, ak@suse.de,
heiko.carstens@de.ibm.com, 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
Subject: Re: [PATCH 6/24] make atomic_read() behave consistently on frv
Date: Fri, 10 Aug 2007 21:29:43 -0700 [thread overview]
Message-ID: <20070811042943.GA13410@linux.vnet.ibm.com> (raw)
In-Reply-To: <E1IJfFe-0003Sq-00@gondolin.me.apana.org.au>
On Sat, Aug 11, 2007 at 08:54:46AM +0800, Herbert Xu wrote:
> Chris Snook <csnook@redhat.com> wrote:
> >
> > cpu_relax() contains a barrier, so it should do the right thing. For
> > non-smp architectures, I'm concerned about interacting with interrupt
> > handlers. Some drivers do use atomic_* operations.
>
> What problems with interrupt handlers? Access to int/long must
> be atomic or we're in big trouble anyway.
Reordering due to compiler optimizations. CPU reordering does not
affect interactions with interrupt handlers on a given CPU, but
reordering due to compiler code-movement optimization does. Since
volatile can in some cases suppress code-movement optimizations,
it can affect interactions with interrupt handlers.
Thanx, Paul
next prev parent reply other threads:[~2007-08-11 4:29 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-09 13:41 [PATCH 6/24] make atomic_read() behave consistently on frv Chris Snook
2007-08-09 16:54 ` Chris Snook
2007-08-10 9:23 ` David Howells
2007-08-10 19:54 ` Chris Snook
2007-08-11 0:54 ` Herbert Xu
2007-08-11 0:54 ` Herbert Xu
2007-08-11 4:29 ` Paul E. McKenney [this message]
2007-08-13 5:15 ` Herbert Xu
2007-08-13 6:03 ` Paul E. McKenney
2007-08-14 5:34 ` Nick Piggin
2007-08-14 7:26 ` Herbert Xu
2007-08-14 17:01 ` Paul E. McKenney
2007-08-14 22:01 ` Arnd Bergmann
2007-08-14 22:43 ` Paul E. McKenney
2007-08-15 13:29 ` Arnd Bergmann
2007-08-15 15:06 ` Michael Buesch
2007-08-15 13:30 ` Nick Piggin
2007-08-15 20:15 ` Paul E. McKenney
2007-08-16 1:09 ` Nick Piggin
2007-08-16 2:27 ` Paul E. McKenney
2007-08-11 8:47 ` David Howells
2007-08-13 6:44 ` Chris Snook
2007-08-14 5:42 ` Nick Piggin
2007-08-15 18:51 ` Segher Boessenkool
2007-08-15 19:18 ` Paul E. McKenney
2007-08-15 19:46 ` Segher Boessenkool
2007-08-15 19:59 ` Paul E. McKenney
2007-08-15 20:13 ` Segher Boessenkool
2007-08-15 20:38 ` Paul E. McKenney
2007-08-15 21:15 ` Segher Boessenkool
2007-08-16 1:20 ` Nick Piggin
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