Re: [RFC PATCH] dynamic_debug: only add header when used

[Luis de Bethencourt]

On 13/07/16 21:32, Andrew Morton wrote:
> On Wed, 13 Jul 2016 18:09:53 +0100 Luis de Bethencourt <luisbg@xxxxxxxxxxxxxxx> wrote:
> 
>> kernel.h header doesn't directly use dynamic debug, instead we can include
>> it in module.c (which used it via kernel.h). printk.h only uses it if
>> CONFIG_DYNAMIC_DEBUG is on, changing the inclusion to only happen in that
>> case.
>>
>> Signed-off-by: Luis de Bethencourt <luisbg@xxxxxxxxxxxxxxx>
>> ---
>> Hi,
>>
>> While studying the problem that surfaced when adding #include <linux/kernel.h>
>> in include/linux/string.h to have access to the MAX_SIZE macro [0]. I noticed
>> that dynamic_debug.h is included in kernel.h even though it isn't necessary.
>> Which in the case of adding kernel.h to string.h would mean a circular
>> dependency.
>>
>> Not entirely sure if there is a reason for this beyond making dynamic debug
>> available to module.c. Which is why I am sending this patch as an RFC.
> 
> It would be good if we can do this.
> 
> What is it in kernel.h that requires dynamic_debug.h?  I tried your
> patch along with
> 
> --- a/kernel/module.c~dynamic_debug-only-add-header-when-used-fix
> +++ a/kernel/module.c
> @@ -60,7 +60,6 @@
>  #include <linux/jump_label.h>
>  #include <linux/pfn.h>
>  #include <linux/bsearch.h>
> -#include <linux/dynamic_debug.h>
>  #include <uapi/linux/module.h>
>  #include "module-internal.h"
>  
> and module.o builds OK.
> 

Hi Andrew,

Thanks for looking at this so quickly.

The kbuild test robot has replied with one driver that needs to be changed
as well for this to work.

Will send a v2 in the next few hours.

Thanks,
Luis