net: Add support for batching network namespace cleanups

- Add exit_list to struct net to support building lists of network
  namespaces to cleanup.

- Add exit_batch to pernet_operations to allow running operations only
  once during a network namespace exit.  Instead of once per network
  namespace.

- Factor opt ops_exit_list and ops_exit_free so the logic with cleanup
  up a network namespace does not need to be duplicated.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 24a8c55..f307e13 100644 (file)
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -43,6 +43,7 @@ struct net {
 #endif
        struct list_head        list;           /* list of network namespaces */
        struct list_head        cleanup_list;   /* namespaces on death row */
+       struct list_head        exit_list;      /* Use only net_mutex */
 
        struct proc_dir_entry   *proc_net;
        struct proc_dir_entry   *proc_net_stat;
@@ -236,6 +237,7 @@ struct pernet_operations {
        struct list_head list;
        int (*init)(struct net *net);
        void (*exit)(struct net *net);
+       void (*exit_batch)(struct list_head *net_exit_list);
        int *id;
        size_t size;
 };

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 9679ad2..6c7f6e0 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -70,6 +70,36 @@ static void ops_free(const struct pernet_operations *ops, struct net *net)
        }
 }
 
+static void ops_exit_list(const struct pernet_operations *ops,
+                         struct list_head *net_exit_list)
+{
+       struct net *net;
+       if (ops->exit) {
+               list_for_each_entry(net, net_exit_list, exit_list)
+                       ops->exit(net);
+       }
+       if (&ops->list == first_device) {
+               LIST_HEAD(dev_kill_list);
+               rtnl_lock();
+               list_for_each_entry(net, net_exit_list, exit_list)
+                       unregister_netdevices(net, &dev_kill_list);
+               unregister_netdevice_many(&dev_kill_list);
+               rtnl_unlock();
+       }
+       if (ops->exit_batch)
+               ops->exit_batch(net_exit_list);
+}
+
+static void ops_free_list(const struct pernet_operations *ops,
+                         struct list_head *net_exit_list)
+{
+       struct net *net;
+       if (ops->size && ops->id) {
+               list_for_each_entry(net, net_exit_list, exit_list)
+                       ops_free(ops, net);
+       }
+}
+
 /*
  * setup_net runs the initializers for the network namespace object.
  */
@@ -78,6 +108,7 @@ static __net_init int setup_net(struct net *net)
        /* Must be called with net_mutex held */
        const struct pernet_operations *ops, *saved_ops;
        int error = 0;
+       LIST_HEAD(net_exit_list);
 
        atomic_set(&net->count, 1);
 
@@ -97,21 +128,14 @@ out_undo:
        /* Walk through the list backwards calling the exit functions
         * for the pernet modules whose init functions did not fail.
         */
+       list_add(&net->exit_list, &net_exit_list);
        saved_ops = ops;
-       list_for_each_entry_continue_reverse(ops, &pernet_list, list) {
-               if (ops->exit)
-                       ops->exit(net);
-               if (&ops->list == first_device) {
-                       LIST_HEAD(dev_kill_list);
-                       rtnl_lock();
-                       unregister_netdevices(net, &dev_kill_list);
-                       unregister_netdevice_many(&dev_kill_list);
-                       rtnl_unlock();
-               }
-       }
+       list_for_each_entry_continue_reverse(ops, &pernet_list, list)
+               ops_exit_list(ops, &net_exit_list);
+
        ops = saved_ops;
        list_for_each_entry_continue_reverse(ops, &pernet_list, list)
-               ops_free(ops, net);
+               ops_free_list(ops, &net_exit_list);
 
        rcu_barrier();
        goto out;
@@ -207,6 +231,7 @@ static void cleanup_net(struct work_struct *work)
        const struct pernet_operations *ops;
        struct net *net, *tmp;
        LIST_HEAD(net_kill_list);
+       LIST_HEAD(net_exit_list);
 
        /* Atomically snapshot the list of namespaces to cleanup */
        spin_lock_irq(&cleanup_list_lock);
@@ -217,8 +242,10 @@ static void cleanup_net(struct work_struct *work)
 
        /* Don't let anyone else find us. */
        rtnl_lock();
-       list_for_each_entry(net, &net_kill_list, cleanup_list)
+       list_for_each_entry(net, &net_kill_list, cleanup_list) {
                list_del_rcu(&net->list);
+               list_add_tail(&net->exit_list, &net_exit_list);
+       }
        rtnl_unlock();
 
        /*
@@ -229,27 +256,12 @@ static void cleanup_net(struct work_struct *work)
        synchronize_rcu();
 
        /* Run all of the network namespace exit methods */
-       list_for_each_entry_reverse(ops, &pernet_list, list) {
-               if (ops->exit) {
-                       list_for_each_entry(net, &net_kill_list, cleanup_list)
-                               ops->exit(net);
-               }
-               if (&ops->list == first_device) {
-                       LIST_HEAD(dev_kill_list);
-                       rtnl_lock();
-                       list_for_each_entry(net, &net_kill_list, cleanup_list)
-                               unregister_netdevices(net, &dev_kill_list);
-                       unregister_netdevice_many(&dev_kill_list);
-                       rtnl_unlock();
-               }
-       }
+       list_for_each_entry_reverse(ops, &pernet_list, list)
+               ops_exit_list(ops, &net_exit_list);
+
        /* Free the net generic variables */
-       list_for_each_entry_reverse(ops, &pernet_list, list) {
-               if (ops->size && ops->id) {
-                       list_for_each_entry(net, &net_kill_list, cleanup_list)
-                               ops_free(ops, net);
-               }
-       }
+       list_for_each_entry_reverse(ops, &pernet_list, list)
+               ops_free_list(ops, &net_exit_list);
 
        mutex_unlock(&net_mutex);
 
@@ -259,8 +271,8 @@ static void cleanup_net(struct work_struct *work)
        rcu_barrier();
 
        /* Finally it is safe to free my network namespace structure */
-       list_for_each_entry_safe(net, tmp, &net_kill_list, cleanup_list) {
-               list_del_init(&net->cleanup_list);
+       list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
+               list_del_init(&net->exit_list);
                net_free(net);
        }
 }
@@ -348,8 +360,9 @@ pure_initcall(net_ns_init);
 static int __register_pernet_operations(struct list_head *list,
                                        struct pernet_operations *ops)
 {
-       struct net *net, *undo_net;
+       struct net *net;
        int error;
+       LIST_HEAD(net_exit_list);
 
        list_add_tail(&ops->list, list);
        if (ops->init || (ops->id && ops->size)) {
@@ -357,6 +370,7 @@ static int __register_pernet_operations(struct list_head *list,
                        error = ops_init(ops, net);
                        if (error)
                                goto out_undo;
+                       list_add_tail(&net->exit_list, &net_exit_list);
                }
        }
        return 0;
@@ -364,36 +378,21 @@ static int __register_pernet_operations(struct list_head *list,
 out_undo:
        /* If I have an error cleanup all namespaces I initialized */
        list_del(&ops->list);
-       if (ops->exit) {
-               for_each_net(undo_net) {
-                       if (net_eq(undo_net, net))
-                               goto undone;
-                       ops->exit(undo_net);
-               }
-       }
-undone:
-       if (ops->size && ops->id) {
-               for_each_net(undo_net) {
-                       if (net_eq(undo_net, net))
-                               goto freed;
-                       ops_free(ops, undo_net);
-               }
-       }
-freed:
+       ops_exit_list(ops, &net_exit_list);
+       ops_free_list(ops, &net_exit_list);
        return error;
 }
 
 static void __unregister_pernet_operations(struct pernet_operations *ops)
 {
        struct net *net;
+       LIST_HEAD(net_exit_list);
 
        list_del(&ops->list);
-       if (ops->exit)
-               for_each_net(net)
-                       ops->exit(net);
-       if (ops->id && ops->size)
-               for_each_net(net)
-                       ops_free(ops, net);
+       for_each_net(net)
+               list_add_tail(&net->exit_list, &net_exit_list);
+       ops_exit_list(ops, &net_exit_list);
+       ops_free_list(ops, &net_exit_list);
 }
 
 #else
@@ -411,9 +410,10 @@ static int __register_pernet_operations(struct list_head *list,
 
 static void __unregister_pernet_operations(struct pernet_operations *ops)
 {
-       if (ops->exit)
-               ops->exit(&init_net);
-       ops_free(ops, &init_net);
+       LIST_HEAD(net_exit_list);
+       list_add(&init_net.exit_list, &net_exit_list);
+       ops_exit_list(ops, &net_exit_list);
+       ops_free_list(ops, &net_exit_list);
 }
 
 #endif /* CONFIG_NET_NS */