3.16.57-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Petr Machata <petrm@xxxxxxxxxxxx>
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@xxxxxxxxxxxx>
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[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@xxxxxxxxxxxxxxx>
---
--- 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);
