From: Daniel Borkmann <redacted>
Date: Thu, 27 Mar 2014 16:38:30 +0100

Quite often it can be useful to test with dummy or similar
devices as a blackhole sink for skbs. Such devices are only
equipped with a single txq, but marked as NETIF_F_LLTX as
they do not require locking their internal queues on xmit
(or implement locking themselves). Therefore, rather use
HARD_TX_{UN,}LOCK API, so that NETIF_F_LLTX will be respected.

trafgen mmap/TX_RING example against dummy device with config
foo: { fill(0xff, 64) } results in the following performance
improvements for such scenarios on an ordinary Core i7/2.80GHz:

 ...

Signed-off-by: Daniel Borkmann <redacted>
Cc: Jesper Dangaard Brouer <redacted>

Applied, nice work.

The only remaining issue is that Eric seems to suggest that a tx
dropped counter bump should be added.  Please submit that as a
follow-on if my reading of his feedback is accurate.