Date: Sat, 3 Jan 2009 21:56:29 +0100
From: Pavel Machek <pavel@suse.cz>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: kernel list <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@osdl.org>,
       mtk.manpages@gmail.com, rdunlap@xenotime.net, linux-doc@vger.kernel.org
Subject: Re: atomics: document that linux expects certain atomic behaviour
	from unsigned long
Message-ID: <20090103205628.GE1666@elf.ucw.cz>
References: <20090103124400.GA1572@ucw.cz> <20090103201955.186974bb@lxorguk.ukuu.org.uk> <20090103202740.GC1666@elf.ucw.cz> <20090103203044.0166b561@lxorguk.ukuu.org.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20090103203044.0166b561@lxorguk.ukuu.org.uk>
User-Agent: Mutt/1.5.18 (2008-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1197
Lines: 29

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/