From e333b1c3cf25fca348422c9ad5cc8db40b4243fa Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Fri, 11 Apr 2025 13:52:30 -0700 Subject: [PATCH] net: Factorise setup_net() and cleanup_net(). When we roll back the changes made by struct pernet_operations.init(), we execute mostly identical sequences in three places. * setup_net() * cleanup_net() * free_exit_list() The only difference between the first two is which list and RCU helpers to use. In setup_net(), an ops could fail on the way, so we need to perform a reverse walk from its previous ops in pernet_list. OTOH, in cleanup_net(), we iterate the full list from tail to head. The former passes the failed ops to list_for_each_entry_continue_reverse(). It's tricky, but we can reuse it for the latter if we pass list_entry() of the head node. Also, synchronize_rcu() and synchronize_rcu_expedited() can be easily switched by an argument. Let's factorise the rollback part in setup_net() and cleanup_net(). In the next patch, ops_undo_list() will be reused for free_exit_list(), and then two arguments (ops_list and hold_rtnl) will differ. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20250411205258.63164-2-kuniyu@amazon.com Signed-off-by: Jakub Kicinski --- net/core/net_namespace.c | 106 +++++++++++++++++++-------------------- 1 file changed, 51 insertions(+), 55 deletions(-) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index b0dfdf791ece5..2612339efd714 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -188,6 +188,53 @@ static void ops_free_list(const struct pernet_operations *ops, } } +static void ops_undo_list(const struct list_head *ops_list, + const struct pernet_operations *ops, + struct list_head *net_exit_list, + bool expedite_rcu, bool hold_rtnl) +{ + const struct pernet_operations *saved_ops; + + if (!ops) + ops = list_entry(ops_list, typeof(*ops), list); + + saved_ops = ops; + + list_for_each_entry_continue_reverse(ops, ops_list, list) + ops_pre_exit_list(ops, net_exit_list); + + /* Another CPU might be rcu-iterating the list, wait for it. + * This needs to be before calling the exit() notifiers, so the + * rcu_barrier() after ops_undo_list() isn't sufficient alone. + * Also the pre_exit() and exit() methods need this barrier. + */ + if (expedite_rcu) + synchronize_rcu_expedited(); + else + synchronize_rcu(); + + if (hold_rtnl) { + LIST_HEAD(dev_kill_list); + + ops = saved_ops; + rtnl_lock(); + list_for_each_entry_continue_reverse(ops, ops_list, list) { + if (ops->exit_batch_rtnl) + ops->exit_batch_rtnl(net_exit_list, &dev_kill_list); + } + unregister_netdevice_many(&dev_kill_list); + rtnl_unlock(); + } + + ops = saved_ops; + list_for_each_entry_continue_reverse(ops, ops_list, list) + ops_exit_list(ops, net_exit_list); + + ops = saved_ops; + list_for_each_entry_continue_reverse(ops, ops_list, list) + ops_free_list(ops, net_exit_list); +} + /* should be called with nsid_lock held */ static int alloc_netid(struct net *net, struct net *peer, int reqid) { @@ -351,9 +398,8 @@ static __net_init void preinit_net(struct net *net, struct user_namespace *user_ static __net_init int setup_net(struct net *net) { /* Must be called with pernet_ops_rwsem held */ - const struct pernet_operations *ops, *saved_ops; + const struct pernet_operations *ops; LIST_HEAD(net_exit_list); - LIST_HEAD(dev_kill_list); int error = 0; preempt_disable(); @@ -376,29 +422,7 @@ out_undo: * 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) - ops_pre_exit_list(ops, &net_exit_list); - - synchronize_rcu(); - - ops = saved_ops; - rtnl_lock(); - list_for_each_entry_continue_reverse(ops, &pernet_list, list) { - if (ops->exit_batch_rtnl) - ops->exit_batch_rtnl(&net_exit_list, &dev_kill_list); - } - unregister_netdevice_many(&dev_kill_list); - rtnl_unlock(); - - ops = saved_ops; - 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_list(ops, &net_exit_list); - + ops_undo_list(&pernet_list, ops, &net_exit_list, false, true); rcu_barrier(); goto out; } @@ -594,11 +618,9 @@ struct task_struct *cleanup_net_task; static void cleanup_net(struct work_struct *work) { - const struct pernet_operations *ops; - struct net *net, *tmp, *last; struct llist_node *net_kill_list; + struct net *net, *tmp, *last; LIST_HEAD(net_exit_list); - LIST_HEAD(dev_kill_list); cleanup_net_task = current; @@ -629,33 +651,7 @@ static void cleanup_net(struct work_struct *work) list_add_tail(&net->exit_list, &net_exit_list); } - /* Run all of the network namespace pre_exit methods */ - list_for_each_entry_reverse(ops, &pernet_list, list) - ops_pre_exit_list(ops, &net_exit_list); - - /* - * Another CPU might be rcu-iterating the list, wait for it. - * This needs to be before calling the exit() notifiers, so - * the rcu_barrier() below isn't sufficient alone. - * Also the pre_exit() and exit() methods need this barrier. - */ - synchronize_rcu_expedited(); - - rtnl_lock(); - list_for_each_entry_reverse(ops, &pernet_list, list) { - if (ops->exit_batch_rtnl) - ops->exit_batch_rtnl(&net_exit_list, &dev_kill_list); - } - unregister_netdevice_many(&dev_kill_list); - rtnl_unlock(); - - /* Run all of the network namespace exit methods */ - 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) - ops_free_list(ops, &net_exit_list); + ops_undo_list(&pernet_list, NULL, &net_exit_list, true, true); up_read(&pernet_ops_rwsem); -- 2.39.5