Disabling an interrupt

Hi, It's long before when I want to enable/disable an interrupt, I call enable_irq()/disable_irq(). However, recently, I do that again. disable_irq() do nothing. I looked into the code and find disable_irq() is pointing to a empty function default_disable(). This change is started from 2.6.20. I want to know what should I do if I want to disable an interrupt now? Thanks. Jacky