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Message-ID: <20090103205628.GE1666@elf.ucw.cz>
Date: Sat, 3 Jan 2009 21:56:29 +0100
From: Pavel Machek <pavel@...e.cz>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
Cc: kernel list <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...l.org>, mtk.manpages@...il.com,
rdunlap@...otime.net, linux-doc@...r.kernel.org
Subject: Re: atomics: document that linux expects certain atomic behaviour
from unsigned long
On Sat 2009-01-03 20:30:44, Alan Cox wrote:
> > If it is okay and linux relies on it, it should be documented.
> >
> > If it is not okay, I guess we should document it, too -- it seems to
> > be common mistake.
>
> A lot of old code did it knowing it was under the BKL, outside of the BKL
> its a very bad idea. There were lots of them in the tty layer and I don't
> doubt there are some left I missed too 8(
I have seen this in new code (some LED driver last time), definitely
no BKL.
Is there concrete architecture where it breaks? I'd expect i386/x86-64
to be safe, and pretty much everyone to be safe as long as that long
is aligned.... or that was the result of arch-maintainers
discussion...
I'd really like to document if it is right or not, so that I can point
people to documentation...
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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