be dropped once the macvtap driver
queue fills up.

This shouldn't be a great problem for the scenario where macvtap
is used to feed a kvm receiver, as the traffic is most likely
external in origin so congestion notification can't be applied
anyway.

Of course, if anybody decides to complain about guest-to-guest
UDP packet loss down the track, then we may have to revisit this.

Incidentally, this patch also fixes a real memory leak when
macvtap_get_queue fails.

Chris Wright noticed that for this patch to work, we need a
non-zero TX queue length.  This patch includes his work to change
the default macvtap TX queue length to 500.

Reported-by: Mark Wagner <mwagner@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
‡šn