From: Jerry Jiang <wjiang@resilience.com>
To: Chris Snook <csnook@redhat.com>
Cc: Chris Friesen <cfriesen@nortel.com>,
"Robert P. J. Day" <rpjday@mindspring.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: why are some atomic_t's not volatile, while most are?
Date: Wed, 8 Aug 2007 10:27:05 +0800 [thread overview]
Message-ID: <20070808102705.9d91a14c.wjiang@resilience.com> (raw)
In-Reply-To: <46B8D6D7.2020206@redhat.com>
On Tue, 07 Aug 2007 16:32:23 -0400
Chris Snook <csnook@redhat.com> wrote:
> > It seems like this would fall more into the case of the arch providing
> > guarantees when using locked/atomic access rather than anything
> > SMP-related, no?.
>
> But if you're not using SMP, the only way you get a race condition is if your
> compiler is reordering instructions that have side effects which are invisible
> to the compiler. This can happen with MMIO registers, but it's not an issue
> with an atomic_t we're declaring in real memory.
>
Under non-SMP, some compilers would reordering instructions as they think
and C standard informally guarantees all operations on volatile data
are executed in the sequence in which they appear in the source code,
right?
So no reordering happens with volatile, right?
-- Jerry
> -- Chris
next prev parent reply other threads:[~2007-08-08 2:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-01 12:49 why are some atomic_t's not volatile, while most are? Robert P. J. Day
2007-08-06 4:35 ` Jerry Jiang
2007-08-06 14:12 ` Chris Snook
2007-08-07 15:51 ` Chris Friesen
2007-08-07 20:32 ` Chris Snook
2007-08-07 21:02 ` Chris Friesen
2007-08-07 21:19 ` Chris Snook
2007-08-07 21:38 ` Chris Friesen
2007-08-07 22:02 ` Chris Snook
2007-08-07 22:46 ` Chris Friesen
2007-08-07 22:06 ` Jan Engelhardt
2007-08-07 22:49 ` Chris Friesen
2007-08-07 22:32 ` Zan Lynx
2007-08-08 1:31 ` Chris Snook
2007-08-08 4:50 ` Chris Friesen
2007-08-08 6:47 ` Chris Snook
2007-08-08 8:16 ` Jerry Jiang
2007-08-08 8:27 ` Jerry Jiang
2007-08-08 20:54 ` Chris Snook
2007-08-09 12:37 ` Robert P. J. Day
2007-08-09 12:52 ` Chris Snook
2007-08-09 18:02 ` Robert P. J. Day
2007-08-09 18:04 ` Robert P. J. Day
2007-08-08 2:27 ` Jerry Jiang [this message]
2007-08-08 5:39 ` Chris Snook
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