On 2/26/18 4:49 PM, Mike Manning wrote:
> Setting an interface into a VRF fails with 'RTNETLINK answers: File
> exists' if one of its VLAN interfaces is already in the same VRF.
> As the VRF is an upper device of the VLAN interface, it is also showing
> up as an upper device of the interface itself. The solution is to
> restrict this check to devices other than master. As only one master
> device can be linked to a device, the check in this case is that the
> upper device (VRF) being linked to is not the same as the master device
> instead of it not being any one of the upper devices.
>
> The following example shows an interface ens12 (with a VLAN interface
> ens12.10) being set into VRF green, which behaves as expected:
>
> # ip link add link ens12 ens12.10 type vlan id 10
> # ip link set dev ens12 master vrfgreen
> # ip link show dev ens12
> 3: ens12: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
> master vrfgreen state UP mode DEFAULT group default qlen 1000
> link/ether 52:54:00:4c:a0:45 brd ff:ff:ff:ff:ff:ff
>
> But if the VLAN interface has previously been set into the same VRF,
> then setting the interface into the VRF fails:
>
> # ip link set dev ens12 nomaster
> # ip link set dev ens12.10 master vrfgreen
> # ip link show dev ens12.10
> 39: ens12.10@ens12: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500
> qdisc noqueue master vrfgreen state UP mode DEFAULT group default
> qlen 1000 link/ether 52:54:00:4c:a0:45 brd ff:ff:ff:ff:ff:ff
> # ip link set dev ens12 master vrfgreen
> RTNETLINK answers: File exists
>
> The workaround is to move the VLAN interface back into the default VRF
> beforehand, but it has to be shut first so as to avoid the risk of
> traffic leaking from the VRF. This fix avoids needing this workaround.
>
> Signed-off-by: Mike Manning <mmann...@att.com>
> ---
> net/core/dev.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index d4362be..2cedf52 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -6396,6 +6396,7 @@ static int __netdev_upper_dev_link(struct net_device
> *dev,
> .linking = true,
> .upper_info = upper_info,
> };
> + struct net_device *master_dev;
> int ret = 0;
>
> ASSERT_RTNL();
> @@ -6407,11 +6408,14 @@ static int __netdev_upper_dev_link(struct net_device
> *dev,
> if (netdev_has_upper_dev(upper_dev, dev))
> return -EBUSY;
>
> - if (netdev_has_upper_dev(dev, upper_dev))
> - return -EEXIST;
> -
> - if (master && netdev_master_upper_dev_get(dev))
> - return -EBUSY;
> + if (!master) {
> + if (netdev_has_upper_dev(dev, upper_dev))
> + return -EEXIST;
> + } else {
> + master_dev = netdev_master_upper_dev_get(dev);
> + if (master_dev)
> + return master_dev == upper_dev ? -EEXIST : -EBUSY;
> + }
>
> ret = call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
> &changeupper_info.info);
>
This looks ok to me. Adding a few others to double check.
