From: Kuniyuki Iwashima <kuniyu@google.com>
Date: Thu, 4 Jun 2026 22:46:31 +0000 (+0000)
Subject: ip6mr: Remove RTNL in ip6mr_rules_init() and ip6mr_net_init().
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2290727b2fdb9f56f6fa2e06b4c5061c4f28e2df;p=thirdparty%2Flinux.git

ip6mr: Remove RTNL in ip6mr_rules_init() and ip6mr_net_init().

When ip6mr_free_table() is called from ip6mr_rules_init() or
ip6mr_net_init(), the netns is not yet published.

Thus, no device should have been registered, and
mroute_clean_tables() will not call mif6_delete(), so
unregister_netdevice_many() is unnecessary.

unregister_netdevice_many() does nothing if the list is empty,
but it requires RTNL due to the unconditional ASSERT_RTNL()
at the entry of unregister_netdevice_many_notify().

Let's remove unnecessary RTNL and ASSERT_RTNL() and instead
add WARN_ON_ONCE() in ip6mr_free_table().

Note that we use a local list for the new WARN_ON_ONCE() because
dev_kill_list passed from ip6mr_rules_exit_rtnl() may have some
devices when other ops->init() fails after ipmr durnig setup_net().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260604224712.3209821-14-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index e9560205b5477..b13ce9c2c463b 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -253,10 +253,7 @@ static int __net_init ip6mr_rules_init(struct net *net)
 	return 0;
 
 err2:
-	rtnl_lock();
 	ip6mr_free_table(mrt, &dev_kill_list);
-	unregister_netdevice_many(&dev_kill_list);
-	rtnl_unlock();
 err1:
 	fib_rules_unregister(ops);
 	return err;
@@ -272,7 +269,6 @@ static void __net_exit ip6mr_rules_exit_rtnl(struct net *net,
 {
 	struct mr_table *mrt, *next;
 
-	ASSERT_RTNL();
 	list_for_each_entry_safe(mrt, next, &net->ipv6.mr6_tables, list) {
 		list_del_rcu(&mrt->list);
 		ip6mr_free_table(mrt, dev_kill_list);
@@ -345,8 +341,6 @@ static void __net_exit ip6mr_rules_exit_rtnl(struct net *net,
 {
 	struct mr_table *mrt = rcu_dereference_protected(net->ipv6.mrt6, 1);
 
-	ASSERT_RTNL();
-
 	RCU_INIT_POINTER(net->ipv6.mrt6, NULL);
 	ip6mr_free_table(mrt, dev_kill_list);
 }
@@ -427,15 +421,19 @@ static void ip6mr_free_table(struct mr_table *mrt,
 			     struct list_head *dev_kill_list)
 {
 	struct net *net = read_pnet(&mrt->net);
+	LIST_HEAD(ip6mr_dev_kill_list);
 
 	WARN_ON_ONCE(!mr_can_free_table(net));
 
 	timer_shutdown_sync(&mrt->ipmr_expire_timer);
 	mroute_clean_tables(mrt, MRT6_FLUSH_MIFS | MRT6_FLUSH_MIFS_STATIC |
 			    MRT6_FLUSH_MFC | MRT6_FLUSH_MFC_STATIC,
-			    dev_kill_list);
+			    &ip6mr_dev_kill_list);
 
 	mr_table_free(mrt);
+
+	WARN_ON_ONCE(!net_initialized(net) && !list_empty(&ip6mr_dev_kill_list));
+	list_splice(&ip6mr_dev_kill_list, dev_kill_list);
 }
 
 #ifdef CONFIG_PROC_FS
@@ -1384,10 +1382,7 @@ static int __net_init ip6mr_net_init(struct net *net)
 proc_cache_fail:
 	remove_proc_entry("ip6_mr_vif", net->proc_net);
 proc_vif_fail:
-	rtnl_lock();
 	ip6mr_rules_exit_rtnl(net, &dev_kill_list);
-	unregister_netdevice_many(&dev_kill_list);
-	rtnl_unlock();
 	ip6mr_rules_exit(net);
 #endif
 ip6mr_rules_fail: