linux-kernel - Re: [PATCH] bitops: Use volatile in generic atomic bitops.

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Message-ID: <CAFbHwiRUKEuK_88+yfUpiWnRBgGKBTpH2Fm7EpzW-dJSiwhHLA@mail.gmail.com>
Date:	Wed, 27 Jul 2011 15:32:43 +0100
From:	Will Newton <will.newton@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] bitops: Use volatile in generic atomic bitops.

On Wed, Jul 27, 2011 at 3:28 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On Wednesday 27 July 2011, Will Newton wrote:
>> >
>> > Have you observed this behavior? The interrupt disable/enable should
>> > always come with a barrier that should prevent the bitops from
>> > leaking out, so I don't see how this causes problems in practice.
>>
>> Yes, although my arch does not have these barriers. Now I see from
>> memory-barriers.txt that lock/unlock are required to implement a
>> compiler barrier, sorry for the noise!
>
> Which architectures is this?

Imagination Technologies META, which is a custom in-house
architecture. No immediate plans to upstream unfortunately. :-/

FWIW I checked all the in-tree architectures and it seems everyone
else gets this right (although I got a bit lost with tile).
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