3.16.57-rc1 review patch. If anyone has any objections, please let me know.
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From: Petr Machata petrm@mellanox.com
commit f6cc9c054e77b9a28d4594bcc201697edb21dfd2 upstream.
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 petrm@mellanox.com Signed-off-by: Ido Schimmel idosch@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net [bwh: Backported to 3.16: Resolve conflict with commit 24fc79798b8d "ip_tunnel: Clamp MTU to bounds on new link", referring to commit 5568cdc368c3 "ip_tunnel: Resolve ipsec merge conflict properly."] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -405,17 +405,26 @@ static struct ip_tunnel *ip_tunnel_creat { struct ip_tunnel *nt; struct net_device *dev; + 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); 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, @@ -962,7 +971,7 @@ int ip_tunnel_newlink(struct net_device nt->parms = *p; 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); @@ -971,15 +980,20 @@ int ip_tunnel_newlink(struct net_device if (tb[IFLA_MTU]) { unsigned int max = 0xfff8 - dev->hard_header_len - nt->hlen;
- dev->mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU, - (unsigned int)(max - sizeof(struct iphdr))); - } else { - dev->mtu = mtu; + mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU, + (unsigned int)(max - sizeof(struct iphdr))); }
+ err = dev_set_mtu(dev, mtu); + if (err) + goto err_dev_set_mtu; + ip_tunnel_add(itn, nt); + return 0;
-out: +err_dev_set_mtu: + unregister_netdevice(dev); +err_register_netdevice: return err; } EXPORT_SYMBOL_GPL(ip_tunnel_newlink);