Header organization/separation rule in kernel

[ozgur@goosey.org (Ozgur)]

Hello,

11.12.2017, 00:32, "Greg KH" <greg@kroah.com>:
> 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?

hm, I think if you use a diff and you would see the why different header file.
for example you development a network card driver and you not be use to linux kernel genetlink header file.

use to network side genetlink.h.

So please check:

#ifndef __NET_GENERIC_NETLINK_H
#define __NET_GENERIC_NETLINK_H

#ifndef __LINUX_GENERIC_NETLINK_H
#define __LINUX_GENERIC_NETLINK_H

#ifndef _UAPI__LINUX_GENERIC_NETLINK_H
#define _UAPI__LINUX_GENERIC_NETLINK_H

they are like the assets that separate and address each others.

> 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

Regards,

Ozgur

>