Date: Thu, 16 Dec 2010 07:50:54 -0800
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: =?iso-8859-1?Q?Am=E9rico?= Wang <xiyou.wangcong@gmail.com>
Cc: Mariusz Kozlowski <mk@lab.zgora.pl>, Dipankar Sarma <dipankar@in.ibm.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rculist: fix borked __list_for_each_rcu() macro
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On Thu, Dec 16, 2010 at 03:38:40PM +0800, Am?rico Wang wrote:
> On Thu, Dec 16, 2010 at 07:02:36AM +0100, Mariusz Kozlowski wrote:
> >On Wed, Dec 15, 2010 at 03:20:05PM -0800, Paul E. McKenney wrote:
> >> On Wed, Dec 15, 2010 at 11:11:12PM +0100, Mariusz Kozlowski wrote:
> >> > This restores parentheses blance.
> >> 
> >> Good catch, queued!!!
> >> 
> >> This does not actually appear to be in use anywhere in the kernel any
> >> more, so I queued this for 2.6.38 rather than in the 2.6.37 urgent queue.
> >> So, just out of curiosity, how did you find this one?
> >
> >Some years ago I wrote a dumb script that walks trees of () and {}.
> >It catches unbalanced trees. It's dumb enough to fail with #ifdef etc,
> >but most of the time it does its job. It reaches unreachable code
> >and unused one too.
> 
> gcc will complain about this, however, in this case, it is used.

Hello, Am?rico!

I did a "git grep -l __list_for_each_rcu" and its output was only:

	include/linux/rculist.h:#define __list_for_each_rcu(pos, head) \

This was in Linus's tree.  And gcc certainly would have failed if
this macro had been used in any recent build.

It really was used some time back, but it appears to me that those
uses no longer exist.

Or are you saying that you have a patch on its way in that needs
this macro?  If so, please point me at it.

							Thanx, Paul
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