Re: [PATCH 0/2] tracing: Move trace_printk.h out of kernel.h

[Randy Dunlap]

On 6/22/26 1:34 AM, Peter Zijlstra wrote:
> On Sun, Jun 21, 2026 at 05:34:30AM -0400, Steven Rostedt wrote:
>> There's been complaints about trace_printk() being defined in kernel.h as it
>> can increase the compilation time. As it is only used by some developers for
>> debugging purposes, it should not be in kernel.h causing lots of wasted CPU
>> cycles for those that do not ever care about it.
>>
>> Instead, add a CONFIG_TRACE_PRINTK_DEBUGGING option that developers that do
>> use it can set and not have to always remember to add #include <linux/trace_printk.h>
>> to the files they add trace_printk() while debugging. It also means that
>> those that do not have that config set will not have to worry about wasted
>> CPU cycles as it is only include in the CFLAGS when the option is set, and
>> its completely ignored otherwise.
> 
> Did you forget your C 101 class? If you use a function, you gotta
> include the relevant header.

Also item #1 in Documentation/process/submit-checklist.rst.

> You don't see userspace saying: 'Hey, you know what, perhaps we should
> add stdio.h to every other header, just in case someone wants to
> printf()' either.
> 
> I really don't understand your argument. Yes, maybe someone will forget
> and then either their editor (if they have a halfway modern setup with
> LSP enabled) or their build will complain, but so what? This is all
> trivial stuff, surely we have more pressing matters to concern outselves
> with?



-- 
~Randy