Re: QUERY: Inclusion of header files in kernel header files

[Stefan Richter <stefanr@s5r6.in-berlin.de>]

Borislav Petkov wrote:
> From: viresh kumar <viresh.linux@gmail.com>
>> Actually this issue is not present only in bus.h, but some other
>> kernel header files.
>> Like: arch/arm/include/asm/clkdev.h don't include list.h file but
>> using struct list_head
>>
>> May be we need to check this in other header files also.
> 
> Well, you should talk to the arm maintainer about that task and whether
> it is desirable.

I agree but feel compelled to add:  While each header file should indeed
include everything that is necessary to allow for arbitrary orders of
inclusion of this header,¹ this is sometimes not possible for core
kernel headers or architecture headers.

An example over which I stumbled a few days ago:  linux/wait.h cannot
easily include linux/sched.h although it uses definitions from it.
There is a direct circular dependency which can be easily resolved, but
there are also dependencies at deeper levels of indirection which cannot
be easily resolved.

----------
¹)  IOW each header should include everything which it uses.  OTOH a
user of that header should not rely on having its own dependencies
included indirectly.
-- 
Stefan Richter
-=====-==-=- --=- =-===
http://arcgraph.de/sr/