Chapter 4. Notification Chains

The kernel's many subsystems are heavily interdependent, so an event detected or generated by one of them could be of interest to others. To fulfill the need for interaction, Linux uses so-called notification chains .

In this chapter, we will see:

• How notification chains are declared and what chains are defined by the networking code

• How a kernel subsystem can register to a notification chain

• How a kernel subsystem generates a notification on a chain

Note that notification chains are used only between kernel subsystems. Notifications between kernel and user space rely on other mechanisms, such as those introduced in Chapter 3.