devlink: change port event netdev notifier from per-net to global

Currently only the network namespace of devlink instance is monitored
for port events. If netdev is moved to a different namespace and then
unregistered, NETDEV_PRE_UNINIT is missed which leads to trigger
following WARN_ON in devl_port_unregister().
WARN_ON(devlink_port->type != DEVLINK_PORT_TYPE_NOTSET);

Fix this by changing the netdev notifier from per-net to global so no
event is missed.

Fixes: 02a68a4 ("net: devlink: track netdev with devlink_port assigned")
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20230206094151.2557264-1-jiri@resnulli.us
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/core/devlink.c

@@ -9979,7 +9979,7 @@ struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
 		goto err_xa_alloc;
 
 	devlink->netdevice_nb.notifier_call = devlink_netdevice_event;
-	ret = register_netdevice_notifier_net(net, &devlink->netdevice_nb);
+	ret = register_netdevice_notifier(&devlink->netdevice_nb);
 	if (ret)
 		goto err_register_netdevice_notifier;
 
@@ -10171,8 +10171,7 @@ void devlink_free(struct devlink *devlink)
 	xa_destroy(&devlink->snapshot_ids);
 	xa_destroy(&devlink->ports);
 
-	WARN_ON_ONCE(unregister_netdevice_notifier_net(devlink_net(devlink),
-						       &devlink->netdevice_nb));
+	WARN_ON_ONCE(unregister_netdevice_notifier(&devlink->netdevice_nb));
 
 	xa_erase(&devlinks, devlink->index);
 
@@ -10503,6 +10502,8 @@ static int devlink_netdevice_event(struct notifier_block *nb,
 		break;
 	case NETDEV_REGISTER:
 	case NETDEV_CHANGENAME:
+		if (devlink_net(devlink) != dev_net(netdev))
+			return NOTIFY_OK;
 		/* Set the netdev on top of previously set type. Note this
 		 * event happens also during net namespace change so here
 		 * we take into account netdev pointer appearing in this
@@ -10512,6 +10513,8 @@ static int devlink_netdevice_event(struct notifier_block *nb,
 					netdev);
 		break;
 	case NETDEV_UNREGISTER:
+		if (devlink_net(devlink) != dev_net(netdev))
+			return NOTIFY_OK;
 		/* Clear netdev pointer, but not the type. This event happens
 		 * also during net namespace change so we need to clear
 		 * pointer to netdev that is going to another net namespace.