Return-path: Received: from stinky.trash.net ([213.144.137.162]:40081 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751632AbZFYOdq (ORCPT ); Thu, 25 Jun 2009 10:33:46 -0400 Message-ID: <4A438AC8.3010907@trash.net> Date: Thu, 25 Jun 2009 16:33:44 +0200 From: Patrick McHardy MIME-Version: 1.0 To: jdb@comx.dk CC: Christoph Lameter , linux-mm@kvack.org, "David S. Miller" , "Paul E. McKenney" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dougthompson@xmission.com, bluesmoke-devel@lists.sourceforge.net, axboe@kernel.dk, christine.caulfield@googlemail.com, Trond.Myklebust@netapp.com, linux-wireless@vger.kernel.org, johannes@sipsolutions.net, yoshfuji@linux-ipv6.org, shemminger@linux-foundation.org, linux-nfs@vger.kernel.org, bfields@fieldses.org, neilb@suse.de, linux-ext4@vger.kernel.org, tytso@mit.edu, adilger@sun.com, netfilter-devel@vger.kernel.org Subject: Re: [PATCH v3 10/10] nf_conntrack: Use rcu_barrier() References: <20090623150330.22490.87327.stgit@localhost> <20090623150444.22490.27931.stgit@localhost> <4A410185.3090706@trash.net> <1245834139.6695.31.camel@localhost.localdomain> <1245836409.6695.35.camel@localhost.localdomain> <4A423108.60109@trash.net> <1245922153.24921.56.camel@localhost.localdomain> <1245924178.24921.61.camel@localhost.localdomain> In-Reply-To: <1245924178.24921.61.camel@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: Jesper Dangaard Brouer wrote: > RCU barriers, rcu_barrier(), is inserted two places. > > In nf_conntrack_expect.c nf_conntrack_expect_fini() before the > kmem_cache_destroy(). Firstly to make sure the callback to the > nf_ct_expect_free_rcu() code is still around. Secondly because I'm > unsure about the consequence of having in flight > nf_ct_expect_free_rcu/kmem_cache_free() calls while doing a > kmem_cache_destroy() slab destroy. > > And in nf_conntrack_extend.c nf_ct_extend_unregister(), inorder to > wait for completion of callbacks to __nf_ct_ext_free_rcu(), which is > invoked by __nf_ct_ext_add(). It might be more efficient to call > rcu_barrier() in nf_conntrack_core.c nf_conntrack_cleanup_net(), but > thats make it more difficult to read the code (as the callback code > in located in nf_conntrack_extend.c). Applied, thanks Jesper.