From: Mike McCormack <redacted>
Date: Thu, 31 Dec 2009 19:55:31 +0900

netif_device_detach() does not take the tx_lock, so it's
 possible that a call to sky2_xmit_frame is still in
 progress after netif_device_detach() is complete.

Take netif_tx_lock() to make sure all transmits have
 stopped while we're disabling the devices and that
 no other CPU is still transmitting a frame after
 we've disabling the device.

Proposed fix for "sky2 panic under load" reported by Berck E. Nash.

Signed-off-by: Mike McCormack <redacted>

Applied to net-next-2.6

Stephen has asked for some further refinements, once that is
all sorted we can think about backporting this to net-2.6
and -stable if necessary.

Thanks.