kernel code reading: struct net has one pointer to loopback dev
kernel code reading: my understanding of hlist
kernel code reading: two important netdev interface

In net driver, we usually call these two functions to create and register a
netdev in the system.
kernel code reading: move general API to other notes

Move register_netdev() and related notes to other file.

So this note focus on the loop device callback.
kernel code reading: net namespace
kernel code reading: kvm code reading
kernel code reading: mm related
kernel code reading: network sch
kernel code reading: EEH on powerpc
kernel code reading: perf cmd_top