From f6cc9c054e77b9a28d4594bcc201697edb21dfd2 Mon Sep 17 00:00:00 2001 From: Petr Machata Date: Thu, 22 Mar 2018 19:53:33 +0200 Subject: 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: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Petr Machata Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller --- net/ipv4/ip_tunnel.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) (limited to 'net/ipv4/ip_tunnel.c') diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index 6d21068f9b55..7b85ffad5d74 100644 --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -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); -- cgit v1.2.3-59-g8ed1b