net: failover: use IFF_NO_ADDRCONF flag to prevent ipv6 addrconf

Similar to Bonding and Team, to prevent ipv6 addrconf with
IFF_NO_ADDRCONF in slave_dev->priv_flags for slave ports
is also needed in net failover.

Note that dev_open(slave_dev) is called in .slave_register,
which is called after the IFF_NO_ADDRCONF flag is set in
failover_slave_register().
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/failover.c

@@ -80,14 +80,14 @@ static int failover_slave_register(struct net_device *slave_dev)
 		goto err_upper_link;
 	}
 
-	slave_dev->priv_flags |= IFF_FAILOVER_SLAVE;
+	slave_dev->priv_flags |= (IFF_FAILOVER_SLAVE | IFF_NO_ADDRCONF);
 
 	if (fops && fops->slave_register &&
 	    !fops->slave_register(slave_dev, failover_dev))
 		return NOTIFY_OK;
 
 	netdev_upper_dev_unlink(slave_dev, failover_dev);
-	slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
+	slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_NO_ADDRCONF);
 err_upper_link:
 	netdev_rx_handler_unregister(slave_dev);
 done:
@@ -121,7 +121,7 @@ int failover_slave_unregister(struct net_device *slave_dev)
 
 	netdev_rx_handler_unregister(slave_dev);
 	netdev_upper_dev_unlink(slave_dev, failover_dev);
-	slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
+	slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_NO_ADDRCONF);
 
 	if (fops && fops->slave_unregister &&
 	    !fops->slave_unregister(slave_dev, failover_dev))