From fae8bd0b07f997b3ae786d451cd37c6207627fd1 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 6 Feb 2024 14:42:57 +0000 Subject: [PATCH] net: add exit_batch_rtnl() method [ Upstream commit fd4f101edbd9f99567ab2adb1f2169579ede7c13 ] Many (struct pernet_operations)->exit_batch() methods have to acquire rtnl. In presence of rtnl mutex pressure, this makes cleanup_net() very slow. This patch adds a new exit_batch_rtnl() method to reduce number of rtnl acquisitions from cleanup_net(). exit_batch_rtnl() handlers are called while rtnl is locked, and devices to be killed can be queued in a list provided as their second argument. A single unregister_netdevice_many() is called right before rtnl is released. exit_batch_rtnl() handlers are called before ->exit() and ->exit_batch() handlers. Signed-off-by: Eric Dumazet Reviewed-by: Antoine Tenart Link: https://lore.kernel.org/r/20240206144313.2050392-2-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 46841c7053e6 ("gtp: Use for_each_netdev_rcu() in gtp_genl_dump_pdp().") Signed-off-by: Sasha Levin --- include/net/net_namespace.h | 3 +++ net/core/net_namespace.c | 31 ++++++++++++++++++++++++++++++- 2 files changed, 33 insertions(+), 1 deletion(-) diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index eb0e7731f3b1c..c41e922fdd97e 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -393,6 +393,9 @@ struct pernet_operations { void (*pre_exit)(struct net *net); void (*exit)(struct net *net); void (*exit_batch)(struct list_head *net_exit_list); + /* Following method is called with RTNL held. */ + void (*exit_batch_rtnl)(struct list_head *net_exit_list, + struct list_head *dev_kill_list); unsigned int *id; size_t size; }; diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index ef19a0eaa55aa..bcf3533cb8ff1 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -331,8 +331,9 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns) { /* Must be called with pernet_ops_rwsem held */ const struct pernet_operations *ops, *saved_ops; - int error = 0; LIST_HEAD(net_exit_list); + LIST_HEAD(dev_kill_list); + int error = 0; refcount_set(&net->count, 1); refcount_set(&net->passive, 1); @@ -365,6 +366,15 @@ out_undo: 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); @@ -569,6 +579,7 @@ static void cleanup_net(struct work_struct *work) struct net *net, *tmp, *last; struct llist_node *net_kill_list; LIST_HEAD(net_exit_list); + LIST_HEAD(dev_kill_list); /* Atomically snapshot the list of namespaces to cleanup */ net_kill_list = llist_del_all(&cleanup_list); @@ -609,6 +620,14 @@ static void cleanup_net(struct work_struct *work) */ synchronize_rcu(); + 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); @@ -1160,7 +1179,17 @@ static void free_exit_list(struct pernet_operations *ops, struct list_head *net_ { ops_pre_exit_list(ops, net_exit_list); synchronize_rcu(); + + if (ops->exit_batch_rtnl) { + LIST_HEAD(dev_kill_list); + + rtnl_lock(); + ops->exit_batch_rtnl(net_exit_list, &dev_kill_list); + unregister_netdevice_many(&dev_kill_list); + rtnl_unlock(); + } ops_exit_list(ops, net_exit_list); + ops_free_list(ops, net_exit_list); } -- 2.47.3