Locking during the poll cq operation can be reduced by locking the cq
while qp is being removed from the qp array.  This also avoids an
extra atomic operation for reference counting.
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>