The slow path calls to the cnic driver are sleepable calls so we
cannot use rcu_read_lock().  Use mutex for these slow path calls
instead.
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Reviewed-by: NBenjamin Li <benli@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>