return from interrupt

基本解释

Execute a Return from Interrupt instruction;
执行中断返回指令；
In 2.6, the driver needs to return IRQ_HANDLED if the interrupt is from that device or IRQ_NONE if it has nothing to do with it.
在2.6中，驱动程序如果要从一个设备上发出一个中断需要返回 IRQ_HANDLED，如果不是的话返回 IRQ_NONE。
If an interrupt keeps coming in and there is no registered handler for that device (for instance, all drivers return IRQ_NONE), then the kernel can block interrupts from that device.
如果一个中断请求不断到来而且没有注册那个设备的处理程序（例如，所有的驱动程序都返回 IRQ_NONE），内核就会忽略来自那个设备的中断。