Interrupts are events generated by peripherals, but, as said earlier, they are not the only events that the kernel can handle. In fact, software interrupts exist, which are similar to hardware interrupts but generated by software. In this book, we'll see two examples of such software interrupts; both of them can be used to safely defer a job for a future time. We'll also have a look at a useful mechanism that a device driver developer can use to catch special kernel events and perform actions as a consequence (for instance, when a network device is enabled, or the system is doing a reboot, and so on).
In this recipe, we will see how to defer a job when a specific event happens within the kernel.
