From: Andi Kleen <andi@firstfloor.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andi Kleen <andi@firstfloor.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 03:25:21 +0200 [thread overview]
Message-ID: <20111028012521.GF25795@one.firstfloor.org> (raw)
In-Reply-To: <1319764761.23112.14.camel@edumazet-laptop>
On Fri, Oct 28, 2011 at 03:19:21AM +0200, Eric Dumazet wrote:
> In commit 4e60c86bd9e (gcc-4.6: mm: fix unused but set warnings)
> Andi forced VM_BUG_ON(cond) to evaluate cond, even if CONFIG_DEBUG_VM is
> not set :
>
> #ifdef CONFIG_DEBUG_VM
> #define VM_BUG_ON(cond) BUG_ON(cond)
> #else
> #define VM_BUG_ON(cond) do { (void)(cond); } while (0)
> #endif
Eventually the warnings were disabled in the Makefile.
So it would be reasonable to just revert that patch now, at least
for VM_BUG_ON, if it costs performance.
>
> So maybe a fix would be to introduce an atomic_read_stable() variant ?
>
> static inline int atomic_read_stable(const atomic_t *v)
> {
> return v->counter;
> }
Seems reasonable too. In fact we usually should have memory barriers
for this anyways which obsolete the volatile.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2011-10-28 1:25 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 [this message]
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
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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