From: Jeff Garzik <jeff@garzik.org>
To: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Krzysztof Halasa <khc@pm.waw.pl>,
David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Paul Sokolovsky <pmiscml@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC/PATCH] doc: volatile considered evil
Date: Tue, 08 May 2007 17:25:40 -0400 [thread overview]
Message-ID: <4640EAD4.9010106@garzik.org> (raw)
In-Reply-To: <4640EB19.6030005@oracle.com>
Randy Dunlap wrote:
> Jeff Garzik wrote:
>> Jeremy Fitzhardinge wrote:
>>> No, David means that "asm volatile (...)" is meaningful and OK to use.
>
> I thought it was OK in readl(), writel(), etc... (and in asm),
> but that's it. (and jiffies)
>
>> In a driver? Highly unlikey it is OK. In a filesystem? Even more
>> unlikely it is OK to use.
>>
>> The set of circumstances where 'volatile' is acceptable is very limited.
>>
>> You will see it used properly in the definitions of writel(), for
>> example. But most drivers using 'volatile' are likely bugs.
Not sure how to interpret your top-posted response :)
It is normal in the definition of writel(), in arch code, but
inappropriate in drivers when they _use_ writel().
If I may generalize, arch code generally knows what it's doing, when it
uses volatile. OTOH, driver authors that use volatile generally do
/not/ know what they are doing.
Jeff
next prev parent reply other threads:[~2007-05-08 21:26 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-01 5:08 [RFC, PATCH 2/4] SoC base drivers: ASIC3 SoC hardware definitions Paul Sokolovsky
2007-05-01 6:56 ` Andrew Morton
2007-05-01 10:27 ` Alan Cox
2007-05-01 12:04 ` Paul Sokolovsky
2007-05-01 12:21 ` Jamey Hicks
2007-05-08 19:14 ` [RFC/PATCH] doc: volatile considered evil Randy Dunlap
2007-05-08 19:18 ` David Rientjes
2007-05-08 20:00 ` Krzysztof Halasa
2007-05-08 20:20 ` David Rientjes
2007-05-08 23:13 ` Randy Dunlap
2007-05-08 23:54 ` David Rientjes
2007-05-09 0:00 ` Randy Dunlap
2007-05-08 21:05 ` Jeremy Fitzhardinge
2007-05-08 21:10 ` Krzysztof Halasa
2007-05-08 21:16 ` Jeff Garzik
2007-05-08 21:26 ` Randy Dunlap
2007-05-08 21:25 ` Jeff Garzik [this message]
2007-05-08 21:20 ` Jeremy Fitzhardinge
2007-05-08 21:27 ` David Rientjes
2007-05-08 21:37 ` Jeremy Fitzhardinge
2007-05-08 21:59 ` David Rientjes
2007-05-08 22:04 ` Jeremy Fitzhardinge
2007-05-08 22:19 ` David Rientjes
2007-05-08 22:29 ` Jeremy Fitzhardinge
2007-05-08 22:35 ` David Rientjes
2007-05-08 23:09 ` Randy Dunlap
2007-05-08 21:29 ` Randy Dunlap
2007-05-08 20:07 ` Satyam Sharma
2007-05-08 23:34 ` [PATCH] " Randy Dunlap
2007-05-09 0:06 ` David Rientjes
2007-05-09 2:08 ` Randy Dunlap
2007-05-09 2:38 ` David Rientjes
2007-05-09 3:15 ` Randy Dunlap
2007-05-09 9:21 ` Alan Cox
2007-05-09 9:26 ` Nick Piggin
2007-05-09 13:31 ` Alan Cox
2007-05-09 10:25 ` David Rientjes
2007-05-09 13:36 ` Alan Cox
2007-05-09 18:41 ` David Rientjes
2007-05-09 20:23 ` Alan Cox
2007-05-09 20:25 ` David Rientjes
2007-05-09 22:47 ` Rob Landley
2007-05-09 8:50 ` Stefan Richter
2007-05-09 15:52 ` Randy Dunlap
2007-05-09 19:04 ` Satyam Sharma
2007-05-09 1:47 ` [RFC/PATCH] " Jonathan Corbet
2007-05-09 9:43 ` Johannes Stezenbach
2007-05-09 19:34 ` Satyam Sharma
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