From 9cb31e9c9c78f147b68b20011869b829aec19203 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
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 <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 7ca4b7af57ca6..17c7a88418345 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -426,6 +426,9 @@ 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 6c6d2a785c004..abf1e1751d6c8 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -314,8 +314,9 @@ 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);
@@ -353,6 +354,15 @@ 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);
@@ -576,6 +586,7 @@ 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);
@@ -616,6 +627,14 @@ 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);
@@ -1159,7 +1178,17 @@ 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);
}
--
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