From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH 6/13] bridge: Add core IGMP snooping support Date: Wed, 10 Mar 2010 08:26:58 -0800 Message-ID: <20100310162658.GI6267@linux.vnet.ibm.com> References: <20100228054012.GA7583@gondor.apana.org.au> <201003092212.59627.arnd@arndb.de> <20100310021410.GD6203@linux.vnet.ibm.com> <201003101041.32518.arnd@arndb.de> <1268217583.2880.2.camel@edumazet-laptop> <20100310104907.GA23752@gondor.apana.org.au> <20100310131317.GA6267@linux.vnet.ibm.com> <20100310140729.GA25704@gondor.apana.org.au> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Dumazet , Arnd Bergmann , "David S. Miller" , netdev@vger.kernel.org, Stephen Hemminger To: Herbert Xu Return-path: Received: from e9.ny.us.ibm.com ([32.97.182.139]:53981 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756284Ab0CJQ1B (ORCPT ); Wed, 10 Mar 2010 11:27:01 -0500 Received: from d01relay01.pok.ibm.com (d01relay01.pok.ibm.com [9.56.227.233]) by e9.ny.us.ibm.com (8.14.3/8.13.1) with ESMTP id o2AGGaYR005240 for ; Wed, 10 Mar 2010 11:16:36 -0500 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay01.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o2AGQxxN089742 for ; Wed, 10 Mar 2010 11:26:59 -0500 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o2AGQw1o012828 for ; Wed, 10 Mar 2010 11:26:59 -0500 Content-Disposition: inline In-Reply-To: <20100310140729.GA25704@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Mar 10, 2010 at 10:07:29PM +0800, Herbert Xu wrote: > On Wed, Mar 10, 2010 at 05:13:18AM -0800, Paul E. McKenney wrote: > > > > If CONFIG_PROVE_RCU is set, rcu_dereference() checks for rcu_read_lock() > > and rcu_dereference_bh() checks for either rcu_read_lock_bh() or BH > > being disabled. Yes, this is a bit restrictive, but there are a few too > > many to check by hand these days. > > Fair enough. We should get those fixed then. In fact I reckon > most of them should be using the BH variant so we might be able > to kill a few rcu_read_lock's which would be a real gain. I have -tip commit a898def29e4119bc01ebe7ca97423181f4c0ea2d that converts some of the rcu_dereference()s in net/core/filter.c, net/core/dev.c, net/decnet/dn_route.c, net/packet/af_packet.c, and net/ipv4/route.c to rcu_dereference_bh(). How should we coordinate the removal of the rcu_read_lock() calls? Thanx, Paul