NOTE: TCP tests are still showing the following warning while running
iperf.
I have analysed the report several times, but it definitely looks like
a false positive to me, so nothing to worry about.
Basically the lockdep engine gets confused thinking that we are
acquiring the lock twice on the same sock, but actually:
1) the kernel is first locking the 'iperf' (user) TCP socket;
2) ovpn is later locking the underlying TCP trasport socket.
So there is NO risk of deadlock (and indeed nothing hangs), but I
couldn't find a way to make the warning go away.