Commit a239e062 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Jakub Kicinski
Browse files

net: Hold __rtnl_net_lock() in (un)?register_netdevice_notifier(). 

(un)?register_netdevice_notifier() hold pernet_ops_rwsem and RTNL,
iterate all netns, and trigger the notifier for all netdev.

Let's hold __rtnl_net_lock() before triggering the notifier.

Note that we will need protection for netdev_chain when RTNL is
removed.  (e.g. blocking_notifier conversion [0] with a lockdep
annotation [1])

Link: https://lore.kernel.org/netdev/20250104063735.36945-2-kuniyu@amazon.com/ [0]
Link: https://lore.kernel.org/netdev/20250105075957.67334-1-kuniyu@amazon.com/

 [1]
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250106070751.63146-2-kuniyu@amazon.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 4ce1aeec

net/core/dev.c

+13 −2
Original line number Diff line number Diff line
@@ -1769,14 +1769,19 @@ int register_netdevice_notifier(struct notifier_block *nb) 


	/* Close race with setup_net() and cleanup_net() */

	down_write(&pernet_ops_rwsem);



	/* When RTNL is removed, we need protection for netdev_chain. */

	rtnl_lock();



	err = raw_notifier_chain_register(&netdev_chain, nb);

	if (err)

		goto unlock;

	if (dev_boot_phase)

		goto unlock;

	for_each_net(net) {

		__rtnl_net_lock(net);

		err = call_netdevice_register_net_notifiers(nb, net);

		__rtnl_net_unlock(net);

		if (err)

			goto rollback;

	}
@@ -1787,8 +1792,11 @@ int register_netdevice_notifier(struct notifier_block *nb) 
	return err;



rollback:

	for_each_net_continue_reverse(net)

	for_each_net_continue_reverse(net) {

		__rtnl_net_lock(net);

		call_netdevice_unregister_net_notifiers(nb, net);

		__rtnl_net_unlock(net);

	}



	raw_notifier_chain_unregister(&netdev_chain, nb);

	goto unlock;
@@ -1821,8 +1829,11 @@ int unregister_netdevice_notifier(struct notifier_block *nb) 
	if (err)

		goto unlock;



	for_each_net(net)

	for_each_net(net) {

		__rtnl_net_lock(net);

		call_netdevice_unregister_net_notifiers(nb, net);

		__rtnl_net_unlock(net);

	}



unlock:

	rtnl_unlock();