Header organization/separation rule in kernel

[greg@kroah.com (Greg KH)]

On Sun, Dec 10, 2017 at 11:21:46PM +0800, Shiyao MA wrote:
> Hi,
> 
> I wonder the header separation rule in kernel.
> To make this question concrete, for example, let's targeting genetlink.h
> 
> It can be found in:
> 
> http://elixir.free-electrons.com/linux/latest/source/include/net/genetlink.h
> http://elixir.free-electrons.com/linux/latest/source/include/linux/genetlink.h
> http://elixir.free-electrons.com/linux/latest/source/include/uapi/linux/genetlink.h
> 
> 
> so basically three parts, in uapi, linux/genetlink.h, and net/genetlink.h.
> 
> I understand the necessity of uapi, but why divide the genetlink.h in
> linux and the net folder?
> What's the benefit of such separation?

Some things are only for the networking subsystem, and some things are
for any other part of the kernel.

Hope this helps,

greg k-h