Re: [PATCH net v2] vti: flush x-netns xfrm cache when vti interface is removed

From: Lance Richardson <redacted>
Date: Tue,  9 Aug 2016 15:29:42 -0400

When executing the script included below, the netns delete operation
hangs with the following message (repeated at 10 second intervals):

  kernel:unregister_netdevice: waiting for lo to become free. Usage count = 1

This occurs because a reference to the lo interface in the "secure" netns
is still held by a dst entry in the xfrm bundle cache in the init netns.

Address this problem by garbage collecting the tunnel netns flow cache
when a cross-namespace vti interface receives a NETDEV_DOWN notification.

 ...

Reported-by: Hangbin Liu <redacted>
Reported-by: Jan Tluka <redacted>
Signed-off-by: Lance Richardson <redacted>
---
v2: Perform garbage collection on NETDEV_DOWN notification (v1 did this 
    in uninit op handler).

Looks good, applied and queued up for -stable, thanks!