From: Ben Hutchings <bhutchings@solarflare.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC] should VM_BUG_ON(cond) really evaluate cond
Date: Fri, 28 Oct 2011 04:29:26 +0100 [thread overview]
Message-ID: <1319772566.6759.27.camel@deadeye> (raw)
In-Reply-To: <1319770376.23112.58.camel@edumazet-laptop>
On Fri, 2011-10-28 at 04:52 +0200, Eric Dumazet wrote:
> Le vendredi 28 octobre 2011 à 02:44 +0100, Ben Hutchings a écrit :
>
> > Whether or not it needs to provide any ordering guarantee, atomic_read()
> > must never read more than once, and I think that requires the volatile
> > qualification. It might be clearer to use the ACCESS_ONCE macro,
> > however.
> >
>
> Where this requirement comes from ?
That is the conventional behaviour of 'atomic' operations, and callers
may depend on it.
> Maybe then introduce atomic_read_once() for users really needing it :)
>
> ACCESS_ONCE will force the read/move instruction I try to avoid :(
[...]
I'm sure you can find some other way to avoid it.
Ben.
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
next prev parent reply other threads:[~2011-10-28 3:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-28 1:19 [RFC] should VM_BUG_ON(cond) really evaluate cond Eric Dumazet
2011-10-28 1:25 ` Andi Kleen
2011-10-28 1:34 ` Linus Torvalds
2011-10-28 1:44 ` Ben Hutchings
2011-10-28 2:52 ` Eric Dumazet
2011-10-28 3:29 ` Ben Hutchings [this message]
2011-10-28 4:43 ` >Re: " Eric Dumazet
2011-10-28 11:37 ` Linus Torvalds
2011-10-28 12:09 ` Eric Dumazet
2011-10-28 12:19 ` Linus Torvalds
2011-10-28 12:40 ` Linus Torvalds
2011-10-28 14:47 ` Eric Dumazet
2011-10-28 14:55 ` Linus Torvalds
2011-10-29 15:43 ` Eric Dumazet
2011-10-29 17:34 ` Linus Torvalds
2011-10-30 8:52 ` Eric Dumazet
2011-10-30 9:59 ` Andi Kleen
2011-10-30 15:16 ` Eric Dumazet
2011-10-30 17:07 ` Linus Torvalds
2011-10-30 17:41 ` Eric Dumazet
2011-10-30 17:48 ` Linus Torvalds
2011-10-30 17:59 ` Eric Dumazet
2011-10-30 18:09 ` Linus Torvalds
2011-11-02 0:14 ` Eric Dumazet
2011-11-01 4:06 ` Stephen Rothwell
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