Best approach to explore the linux source code

[Umair Khan]

Hi everyone,

I'm a final year undergraduate student. I've been spending a lot of
time with OS books these days.
I've been reading about the internals of the Linux kernel and drivers
in the books. But, I've never really seen them in action except the
drivers. Hacking a driver is easy.

Is there any good approach/tutorial to walk me through the source code
of the kernel ?

Also, I'm using a self built linux kernel 4.2 on my laptop. Is there
any way that I can contribute upstream to the kernel. I'm using 4.2 in
the hope to find bugs in driver stuffs. I haven't found any yet.

Thanks
Umair
Delhi Technological University, India