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Commit f6cc9c05 authored by Petr Machata's avatar Petr Machata Committed by David S. Miller
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ip_tunnel: Emit events for post-register MTU changes 



For tunnels created with IFLA_MTU, MTU of the netdevice is set by
rtnl_create_link() (called from rtnl_newlink()) before the device is
registered. However without IFLA_MTU that's not done.

rtnl_newlink() proceeds by calling struct rtnl_link_ops.newlink, which
via ip_tunnel_newlink() calls register_netdevice(), and that emits
NETDEV_REGISTER. Thus any listeners that inspect the netdevice get the
MTU of 0.

After ip_tunnel_newlink() corrects the MTU after registering the
netdevice, but since there's no event, the listeners don't get to know
about the MTU until something else happens--such as a NETDEV_UP event.
That's not ideal.

So instead of setting the MTU directly, go through dev_set_mtu(), which
takes care of distributing the necessary NETDEV_PRECHANGEMTU and
NETDEV_CHANGEMTU events.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarPetr Machata <petrm@mellanox.com>
Signed-off-by: default avatarIdo Schimmel <idosch@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f36b7534

net/ipv4/ip_tunnel.c

+21 −5
Original line number Diff line number Diff line
@@ -362,13 +362,18 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net, 
	struct ip_tunnel *nt;

	struct net_device *dev;

	int t_hlen;

	int mtu;

	int err;



	BUG_ON(!itn->fb_tunnel_dev);

	dev = __ip_tunnel_create(net, itn->fb_tunnel_dev->rtnl_link_ops, parms);

	if (IS_ERR(dev))

		return ERR_CAST(dev);



	dev->mtu = ip_tunnel_bind_dev(dev);

	mtu = ip_tunnel_bind_dev(dev);

	err = dev_set_mtu(dev, mtu);

	if (err)

		goto err_dev_set_mtu;



	nt = netdev_priv(dev);

	t_hlen = nt->hlen + sizeof(struct iphdr);
@@ -376,6 +381,10 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net, 
	dev->max_mtu = 0xFFF8 - dev->hard_header_len - t_hlen;

	ip_tunnel_add(itn, nt);

	return nt;



err_dev_set_mtu:

	unregister_netdevice(dev);

	return ERR_PTR(err);

}



int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
@@ -1102,17 +1111,24 @@ int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[], 
	nt->fwmark = fwmark;

	err = register_netdevice(dev);

	if (err)

		goto out;

		goto err_register_netdevice;



	if (dev->type == ARPHRD_ETHER && !tb[IFLA_ADDRESS])

		eth_hw_addr_random(dev);



	mtu = ip_tunnel_bind_dev(dev);

	if (!tb[IFLA_MTU])

		dev->mtu = mtu;

	if (!tb[IFLA_MTU]) {

		err = dev_set_mtu(dev, mtu);

		if (err)

			goto err_dev_set_mtu;

	}



	ip_tunnel_add(itn, nt);

out:

	return 0;



err_dev_set_mtu:

	unregister_netdevice(dev);

err_register_netdevice:

	return err;

}

EXPORT_SYMBOL_GPL(ip_tunnel_newlink);