When the peer link is created, its "iflink" information is not
advertised through netlink. If a user is maintaining a cache from all
updates, it will miss this information:

    2: veth0@NONE: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group 
default
        link/ether ae:0e:08:af:fb:a0 brd ff:ff:ff:ff:ff:ff
    3: veth1@veth0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN 
group default
        link/ether 3a:31:f1:36:2e:e5 brd ff:ff:ff:ff:ff:ff

To avoid this situation, the peer link is only configured after both
interfaces are tied together:

    3: veth0@veth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group 
default
        link/ether ee:0d:80:46:36:fe brd ff:ff:ff:ff:ff:ff
    4: veth1@veth0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN 
group default
        link/ether ba:25:bc:7a:0d:c8 brd ff:ff:ff:ff:ff:ff

Signed-off-by: Vincent Bernat <vinc...@bernat.im>
---
 drivers/net/veth.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index f37a6e61d4ad..9726c4dbf659 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -432,10 +432,6 @@ static int veth_newlink(struct net *src_net, struct 
net_device *dev,
 
        netif_carrier_off(peer);
 
-       err = rtnl_configure_link(peer, ifmp);
-       if (err < 0)
-               goto err_configure_peer;
-
        /*
         * register dev last
         *
@@ -466,6 +462,10 @@ static int veth_newlink(struct net *src_net, struct 
net_device *dev,
 
        priv = netdev_priv(peer);
        rcu_assign_pointer(priv->peer, dev);
+
+       err = rtnl_configure_link(peer, ifmp);
+       if (err < 0)
+               goto err_configure_peer;
        return 0;
 
 err_register_dev:
-- 
2.8.1

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