Messages in this thread Patch in this message |  | | Subject | [PATCH v2 10/10] nf_conntrack: Use rcu_barrier() and fix kmem_cache_create flags | From | Jesper Dangaard Brouer <> | Date | Wed, 24 Jun 2009 11:40:09 +0200 |
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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 <hawk@comx.dk> ---
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);
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