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
Date: Sat, 3 Jan 2009 21:27:40 +0100 [thread overview]
Message-ID: <20090103202740.GC1666@elf.ucw.cz> (raw)
In-Reply-To: <20090103201955.186974bb@lxorguk.ukuu.org.uk>
On Sat 2009-01-03 20:19:55, Alan Cox wrote:
> On Sat, 3 Jan 2009 13:44:00 +0100
> Pavel Machek <pavel@suse.cz> wrote:
>
> > Linux relies on unsigned long to behave like atomic for read/write.
>
> Actually it isn't that simple and this advice shouldn't be given IMHO.
>
> unsigned long is not the same as atomic in several respects including
> ordering and caching of the result.
Ok... I keep seeing patches using int/long instead of atomic and
claiming that it is okay.
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.
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2009-01-03 20:25 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-03 12:44 atomics: document that linux expects certain atomic behaviour from unsigned long Pavel Machek
2009-01-03 20:19 ` Alan Cox
2009-01-03 20:27 ` Pavel Machek [this message]
2009-01-03 20:30 ` Alan Cox
2009-01-03 20:56 ` Pavel Machek
2009-01-03 23:01 ` david
2009-01-03 23:14 ` Alan Cox
2009-01-05 10:54 ` Nick Piggin
2009-01-05 11:23 ` Alan Cox
2009-01-05 12:00 ` Nick Piggin
2009-01-05 16:05 ` Paul E. McKenney
2009-01-05 16:25 ` Nick Piggin
2009-01-05 17:30 ` Paul E. McKenney
2009-01-05 18:25 ` Nick Piggin
2009-01-05 22:01 ` Paul E. McKenney
2009-01-03 23:53 ` Robert Hancock
2009-01-04 18:05 ` Tilman Schmidt
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