net: Allow to create links with given ifindex
Currently the RTM_NEWLINK results in -EOPNOTSUPP if the ifinfomsg->ifi_index
is not zero. I propose to allow requesting ifindices on link creation. This
is required by the checkpoint-restore to correctly restore a net namespace
(i.e. -- a container).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index f91abf8..3ca300d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5579,7 +5579,12 @@
}
}
- dev->ifindex = dev_new_index(net);
+ ret = -EBUSY;
+ if (!dev->ifindex)
+ dev->ifindex = dev_new_index(net);
+ else if (__dev_get_by_index(net, dev->ifindex))
+ goto err_uninit;
+
if (dev->iflink == -1)
dev->iflink = dev->ifindex;
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index db037c9..34d975b 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1812,8 +1812,6 @@
return -ENODEV;
}
- if (ifm->ifi_index)
- return -EOPNOTSUPP;
if (tb[IFLA_MAP] || tb[IFLA_MASTER] || tb[IFLA_PROTINFO])
return -EOPNOTSUPP;
@@ -1839,10 +1837,14 @@
return PTR_ERR(dest_net);
dev = rtnl_create_link(net, dest_net, ifname, ops, tb);
-
- if (IS_ERR(dev))
+ if (IS_ERR(dev)) {
err = PTR_ERR(dev);
- else if (ops->newlink)
+ goto out;
+ }
+
+ dev->ifindex = ifm->ifi_index;
+
+ if (ops->newlink)
err = ops->newlink(net, dev, tb, data);
else
err = register_netdevice(dev);