5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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 edumazet@google.com Reviewed-by: Antoine Tenart atenart@kernel.org Link: https://lore.kernel.org/r/20240206144313.2050392-2-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Stable-dep-of: 46841c7053e6 ("gtp: Use for_each_netdev_rcu() in gtp_genl_dump_pdp().") Signed-off-by: Sasha Levin sashal@kernel.org --- 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 167e390ac9d4e..0d61b452b9082 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -382,6 +382,9 @@ 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 c4bcedc06822b..e6585a758edd4 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -325,8 +325,9 @@ 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); @@ -359,6 +360,15 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
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); @@ -563,6 +573,7 @@ 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); @@ -603,6 +614,14 @@ 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); @@ -1150,7 +1169,17 @@ 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); }