As previously reported the ArcNet driver didn't work with Preempt and SMB
on.  They do now.  I have changed the locking system from being a global
arcnet lock to being a lock per device.  I used the lock in
dev->hard_start_xmit = arcnet_send_packet.  

Furthermore I added the 'CAP mode' encapsulation.  As far as I see it it is
the only encapsulation which actually makes ArcNet usefull over ethernet. 
Previously, the driver just ignored the hardware transmit status, now you
can get hardware acknowledge and excessive nacks back to userspace via a
raw socket.  The capmode.c is nearly just a copy of arc-rawmode.c.  The
difference is that it inserts a ack_tx() handle into the general driver
framework.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>