From: Jesper Dangaard Brouer Subject: [PATCH v2 10/10] nf_conntrack: Use rcu_barrier() and fix kmem_cache_create flags Date: Wed, 24 Jun 2009 11:40:09 +0200 Message-ID: <1245836409.6695.35.camel@localhost.localdomain> References: <20090623150330.22490.87327.stgit@localhost> <20090623150444.22490.27931.stgit@localhost> <4A410185.3090706@trash.net> <1245834139.6695.31.camel@localhost.localdomain> Reply-To: jdb@comx.dk Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: "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: Received: from lanfw001a.cxnet.dk ([87.72.215.196]:41448 "EHLO lanfw001a.cxnet.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751515AbZFXJkI (ORCPT ); Wed, 24 Jun 2009 05:40:08 -0400 In-Reply-To: <1245834139.6695.31.camel@localhost.localdomain> Sender: linux-ext4-owner@vger.kernel.org List-ID: Adjusting SLAB_DESTROY_BY_RCU flags. kmem_cache_create("nf_conntrack", ...) does not need the SLAB_DESTROY_BY_RCU flag. But the kmem_cache_create("nf_conntrack_expect", ...) should use the SLAB_DESTROY_BY_RCU flag, because it uses a call_rcu() callback to invoke kmem_cache_free(). RCU barriers, rcu_barrier(), is inserted two places. In nf_conntrack_expect.c nf_conntrack_expect_fini() before the kmem_cache_destroy(), even though the use of the SLAB_DESTROY_BY_RCU flag, because slub does not (currently) handle rcu sync correctly. 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_core.c | 2 +- net/netfilter/nf_conntrack_expect.c | 11 +++++++++-- net/netfilter/nf_conntrack_extend.c | 2 +- 3 files changed, 11 insertions(+), 4 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 5f72b94..438ce84 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1242,7 +1242,7 @@ static int nf_conntrack_init_init_net(void) nf_conntrack_cachep = kmem_cache_create("nf_conntrack", sizeof(struct nf_conn), - 0, SLAB_DESTROY_BY_RCU, NULL); + 0, 0, NULL); if (!nf_conntrack_cachep) { printk(KERN_ERR "Unable to create nf_conn slab cache\n"); ret = -ENOMEM; diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c index afde8f9..56227c2 100644 --- a/net/netfilter/nf_conntrack_expect.c +++ b/net/netfilter/nf_conntrack_expect.c @@ -593,7 +593,7 @@ int nf_conntrack_expect_init(struct net *net) if (net_eq(net, &init_net)) { nf_ct_expect_cachep = kmem_cache_create("nf_conntrack_expect", sizeof(struct nf_conntrack_expect), - 0, 0, NULL); + 0, SLAB_DESTROY_BY_RCU, NULL); if (!nf_ct_expect_cachep) goto err2; } @@ -617,8 +617,15 @@ 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)) { + /* hawk@comx.dk 2009-06-24: The rcu_barrier() can be + * removed once the sl*b allocators has been fixed + * regarding handling the SLAB_DESTROY_BY_RCU flag + * correctly. + */ + 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);