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Message-ID: <20240206144313.2050392-2-edumazet@google.com>
Date: Tue, 6 Feb 2024 14:42:57 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Antoine Tenart <atenart@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v4 net-next 01/15] net: add exit_batch_rtnl() method
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@...gle.com>
---
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 cd0c2eedbb5e9ddcbd5e0a37e2eb7e0cf57495d5..20c34bd7a07783a9a13696fd74b41eff1ff860a8 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -448,6 +448,9 @@ 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 72799533426b6162256d7c4eef355af96c66e844..233ec0cdd0111d5ca21c6f8a66f4c1f3fbc4657b 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -318,8 +318,9 @@ 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->ns.count, 1);
ref_tracker_dir_init(&net->refcnt_tracker, 128, "net refcnt");
@@ -357,6 +358,15 @@ 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);
@@ -573,6 +583,7 @@ 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);
@@ -613,6 +624,14 @@ 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);
@@ -1193,7 +1212,17 @@ 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);
}
--
2.43.0.594.gd9cf4e227d-goog
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