From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760698AbYBLBQZ (ORCPT ); Mon, 11 Feb 2008 20:16:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754006AbYBLBQP (ORCPT ); Mon, 11 Feb 2008 20:16:15 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:36544 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752843AbYBLBQO (ORCPT ); Mon, 11 Feb 2008 20:16:14 -0500 Date: Mon, 11 Feb 2008 17:16:45 -0800 (PST) Message-Id: <20080211.171645.74019568.davem@davemloft.net> To: shemminger@vyatta.com Cc: paulmck@us.ibm.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] fib_trie: rcu_assign_pointer warning fix From: David Miller In-Reply-To: <20080211165954.2f1b3a9b@extreme> References: <20080211165954.2f1b3a9b@extreme> X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stephen Hemminger Date: Mon, 11 Feb 2008 16:59:54 -0800 linux-kernel added to CC:, any change to generic kernel infrastructure should be posted there > Eliminate warnings when rcu_assign_pointer is used with unsigned long. > It is reasonable to use RCU with non-pointer values so allow it for general > use. Add a comment to explain the if test. > > Signed-off-by: Stephen Hemminger > --- > include/linux/rcupdate.h | 13 +++++++------ > 1 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index 37a642c..c44ac87 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -172,14 +172,15 @@ struct rcu_head { > * structure after the pointer assignment. More importantly, this > * call documents which pointers will be dereferenced by RCU read-side > * code. > + * > + * If value is the NULL (constant 0), then no barrier is needed. > */ > > -#define rcu_assign_pointer(p, v) \ > - ({ \ > - if (!__builtin_constant_p(v) || \ > - ((v) != NULL)) \ > - smp_wmb(); \ > - (p) = (v); \ > +#define rcu_assign_pointer(p, v) \ > + ({ \ > + if (!(__builtin_constant_p(v) && v)) \ > + smp_wmb(); \ > + (p) = (v); \ > }) > > /** > -- > 1.5.3.8 >