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

[Andrew Morton]

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.