e1000e (and e1000, igb, ixgbe, ixgb) all do a series of operations each
time a multicast address is added.  The flow goes something like

1) stack adds one multicast address
2) stack passes whole current list of unicast and multicast addresses to
   driver
3) driver clears entire list in hardware
4) driver programs each multicast address using iomem in a loop

This was causing multicast packets to be lost during the reprogramming
process.

reference with test program:
http://kerneltrap.org/mailarchive/linux-netdev/2009/3/14/5160514/thread

Thanks to Dave Boutcher for his report and test program.

This driver fix prepares an array all at once in memory and programs it in
one shot to the hardware, not requiring an "erase" cycle.  It would still
be possible for packets to be dropped while the receiver is off during
reprogramming.
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
CC: Dave Boutcher <daveboutcher@gmail.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>