[lxc-devel] Problem when using same vlan.id for multiple vlan interfaces

[Serge Hallyn]

Quoting Axel Neumann (neumann at cgws.de):
> Hello,
> 
> First, thanks a lot for your good work!
> We are using LXC in the CONFINE project (confine-project.eu) to provide 
> researchers with a virtualized linux evironment in a distributed testbed.
> 
> We found a problem when a container config looks like this (uses the 
> same vlan id for several type=vlan container interfaces):
> 
> lxc.network.type      = vlan
> lxc.network.flags     = up
> lxc.network.link      = eth1
> lxc.network.vlan.id   = 3842
> lxc.network.name      = iso0
> 
> lxc.network.type      = vlan
> lxc.network.flags     = up
> lxc.network.link      = eth2
> lxc.network.vlan.id   = 3842
> lxc.network.name      = iso1
> 
> Then, during the instantiation of the vlan interfaces an error occurs 
> because the lxc code tries to assign the same name to both of them 
> before it is bound into the container.
> 
> Maybe you can have a look at the  following patch which solves the problem
> (see also here: 
> https://github.com/axn/lxc/commit/32fb8a007a95ad4beb9d9d7dade032a50f5da0db 
>   )
> and consider this or an alternative solution for your 0.8.0 branch.
> 
> Thanks a lot
> /axel

Acked-by: Serge E. Hallyn <serge at hallyn.com>

Looks reasonable.  Thanks

> 
> neumann at sid:/usr/src/lxc/lxc.git$ git diff HEAD^
> diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> index e8088bb..4f21464 100644
> --- a/src/lxc/conf.c
> +++ b/src/lxc/conf.c
> @@ -1733,13 +1733,14 @@ static int instanciate_vlan(struct lxc_handler 
> *handler, struct lxc_netdev *netd
>   {
>          char peer[IFNAMSIZ];
>          int err;
> +        static uint16_t vlan_cntr = 0;
> 
>          if (!netdev->link) {
>                  ERROR("no link specified for vlan netdev");
>                  return -1;
> -       }
> +        }
> 
> -       snprintf(peer, sizeof(peer), "vlan%d", netdev->priv.vlan_attr.vid);
> +        snprintf(peer, sizeof (peer), "vlan%d-%d", 
> netdev->priv.vlan_attr.vid, vlan_cntr++);
> 
>          err = lxc_vlan_create(netdev->link, peer, 
> netdev->priv.vlan_attr.vid);
>          if (err) {
> 
> 
> 
> 
> 
> 
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