ip_tunnel: Emit events for post-register MTU changes (f6cc9c05) · Commits · 戴 / test

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: ("Linux-2.6.12-rc2") Signed-off-by:

Petr Machata <petrm@mellanox.com> Signed-off-by:

Ido Schimmel <idosch@mellanox.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

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);

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