From: Jesper Dangaard Brouer Subject: [PATCH v3 10/10] nf_conntrack: Use rcu_barrier() Date: Thu, 25 Jun 2009 12:02:58 +0200 Message-ID: <1245924178.24921.61.camel@localhost.localdomain> 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> Reply-To: jdb@comx.dk Mime-Version: 1.0 Content-Type: text/plain 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 To: Patrick McHardy Return-path: In-Reply-To: <1245922153.24921.56.camel@localhost.localdomain> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, 2009-06-25 at 11:29 +0200, Jesper Dangaard Brouer wrote: > Should I make two different patchs? Here is the single patch... Patrick tell me if you want it split up? [PATCH v3 10/10] nf_conntrack: Use rcu_barrier() From: Jesper Dangaard Brouer 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). Signed-off-by: Jesper Dangaard Brouer --- net/netfilter/nf_conntrack_expect.c | 4 +++- net/netfilter/nf_conntrack_extend.c | 2 +- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c index afde8f9..2032dfe 100644 --- a/net/netfilter/nf_conntrack_expect.c +++ b/net/netfilter/nf_conntrack_expect.c @@ -617,8 +617,10 @@ err1: void nf_conntrack_expect_fini(struct net *net) { exp_proc_remove(net); - if (net_eq(net, &init_net)) + if (net_eq(net, &init_net)) { + rcu_barrier(); /* Wait for call_rcu() before destroy */ kmem_cache_destroy(nf_ct_expect_cachep); + } nf_ct_free_hashtable(net->ct.expect_hash, net->ct.expect_vmalloc, nf_ct_expect_hsize); } diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c index 4b2c769..fef95be 100644 --- a/net/netfilter/nf_conntrack_extend.c +++ b/net/netfilter/nf_conntrack_extend.c @@ -186,6 +186,6 @@ void nf_ct_extend_unregister(struct nf_ct_ext_type *type) rcu_assign_pointer(nf_ct_ext_types[type->id], NULL); update_alloc_size(type); mutex_unlock(&nf_ct_ext_type_mutex); - synchronize_rcu(); + rcu_barrier(); /* Wait for completion of call_rcu()'s */ } EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);