Dave, I am sorry, plz disregard the patch :(

- if the file is a part of the kernel, __exit (and pernet_unregister)
  will never called and should be dropped
- if the file is a part of a module, __init is NOT dropped on the
  module loading stage

So, we can still make embedded people happy :) Thanks Pavel to pointing
me this out.

Denis V. Lunev wrote:
> The discussion with Eric W. Biederman reveals that the concept for
> __net_initdata is bogus. The ->exit method of pernet_operations
> should be called during module exit.
> 
> So, discard this attribute.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>