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 e9560205b5477382a96bf599ee753421e20f5ce6..b13ce9c2c463b46631a582eb4b818f46518dac1f 100644 (file)
--- 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: