netfilter: nf_conntrack: speed up module removal path if netns in use

The patch introduces nf_conntrack_cleanup_net_list(), which cleanups
nf_conntrack for a list of netns and calls synchronize_net() only once
for them all. This should reduce netns destruction time.

I've measured cleanup time for 1k dummy net ns. Here are the results:

 <without the patch>
 # modprobe nf_conntrack
 # time modprobe -r nf_conntrack

 real	0m10.337s
 user	0m0.000s
 sys	0m0.376s

 <with the patch>
 # modprobe nf_conntrack
 # time modprobe -r nf_conntrack

 real    0m5.661s
 user    0m0.000s
 sys     0m0.216s

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h
index 930275fa2ea68f082e5974586abc39c5138706c4..fb2b6234e9375846bdb37727717c7dbd432550d9 100644 (file)
--- a/include/net/netfilter/nf_conntrack_core.h
+++ b/include/net/netfilter/nf_conntrack_core.h
@@ -27,6 +27,7 @@ extern unsigned int nf_conntrack_in(struct net *net,
 
 extern int nf_conntrack_init_net(struct net *net);
 extern void nf_conntrack_cleanup_net(struct net *net);
+extern void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list);
 
 extern int nf_conntrack_proto_pernet_init(struct net *net);
 extern void nf_conntrack_proto_pernet_fini(struct net *net);

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 1068deb97c8b60a24ff2595c8238259e3cbed79c..007e8c43d19ad6f8eb98aacd37505dfb33710744 100644 (file)
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1365,30 +1365,48 @@ void nf_conntrack_cleanup_end(void)
  */
 void nf_conntrack_cleanup_net(struct net *net)
 {
+       LIST_HEAD(single);
+
+       list_add(&net->exit_list, &single);
+       nf_conntrack_cleanup_net_list(&single);
+}
+
+void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
+{
+       int busy;
+       struct net *net;
+
        /*
         * This makes sure all current packets have passed through
         *  netfilter framework.  Roll on, two-stage module
         *  delete...
         */
        synchronize_net();
- i_see_dead_people:
-       nf_ct_iterate_cleanup(net, kill_all, NULL);
-       nf_ct_release_dying_list(net);
-       if (atomic_read(&net->ct.count) != 0) {
+i_see_dead_people:
+       busy = 0;
+       list_for_each_entry(net, net_exit_list, exit_list) {
+               nf_ct_iterate_cleanup(net, kill_all, NULL);
+               nf_ct_release_dying_list(net);
+               if (atomic_read(&net->ct.count) != 0)
+                       busy = 1;
+       }
+       if (busy) {
                schedule();
                goto i_see_dead_people;
        }
 
-       nf_ct_free_hashtable(net->ct.hash, net->ct.htable_size);
-       nf_conntrack_proto_pernet_fini(net);
-       nf_conntrack_helper_pernet_fini(net);
-       nf_conntrack_ecache_pernet_fini(net);
-       nf_conntrack_tstamp_pernet_fini(net);
-       nf_conntrack_acct_pernet_fini(net);
-       nf_conntrack_expect_pernet_fini(net);
-       kmem_cache_destroy(net->ct.nf_conntrack_cachep);
-       kfree(net->ct.slabname);
-       free_percpu(net->ct.stat);
+       list_for_each_entry(net, net_exit_list, exit_list) {
+               nf_ct_free_hashtable(net->ct.hash, net->ct.htable_size);
+               nf_conntrack_proto_pernet_fini(net);
+               nf_conntrack_helper_pernet_fini(net);
+               nf_conntrack_ecache_pernet_fini(net);
+               nf_conntrack_tstamp_pernet_fini(net);
+               nf_conntrack_acct_pernet_fini(net);
+               nf_conntrack_expect_pernet_fini(net);
+               kmem_cache_destroy(net->ct.nf_conntrack_cachep);
+               kfree(net->ct.slabname);
+               free_percpu(net->ct.stat);
+       }
 }
 
 void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)

diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 6bcce401fd1c5ddfbc3fe00bb45ab87a72ab9fb2..6c69fbdb8361ad0ed717bc40a52462f888df57e7 100644 (file)
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -545,16 +545,20 @@ out_init:
        return ret;
 }
 
-static void nf_conntrack_pernet_exit(struct net *net)
+static void nf_conntrack_pernet_exit(struct list_head *net_exit_list)
 {
-       nf_conntrack_standalone_fini_sysctl(net);
-       nf_conntrack_standalone_fini_proc(net);
-       nf_conntrack_cleanup_net(net);
+       struct net *net;
+
+       list_for_each_entry(net, net_exit_list, exit_list) {
+               nf_conntrack_standalone_fini_sysctl(net);
+               nf_conntrack_standalone_fini_proc(net);
+       }
+       nf_conntrack_cleanup_net_list(net_exit_list);
 }
 
 static struct pernet_operations nf_conntrack_net_ops = {
-       .init = nf_conntrack_pernet_init,
-       .exit = nf_conntrack_pernet_exit,
+       .init           = nf_conntrack_pernet_init,
+       .exit_batch     = nf_conntrack_pernet_exit,
 };
 
 static int __init nf_conntrack_standalone_init(void)