Besides the exercise of using the current macro, a key point behind this kernel module (ch6/current_affairs) is to clearly show you the monolithic nature of the Linux OS. In the preceding code, we saw that when we performed the insmod(8) process on our kernel module file (current_affairs.ko), it got inserted into the kernel and its init code path ran; who ran it? Ah, that question is answered by checking the output: the insmod process itself ran it in process context, thus proving the monolithic nature of the Linux kernel! (Ditto with the rmmod(8) process and the cleanup code path; it was run by the rmmod process in process context.)
Note carefully and clearly: there is no "kernel" (or kernel thread) that executes the code of the kernel module, it's the user space process (or thread) itself that, by issuing system calls (recall that both the insmod(8) and rmmod(8) utilities...
