Avoid taking the CQ table lock in the fast path path by using
synchronize_irq() after removing a CQ from the table to make sure that
no completion events are still in progress.  This gets a nice speedup
(about 4%) in IP over IB on my hardware.
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <roland@topspin.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>