Re: [PATCH v1] xen/console: remove __printk_ratelimit()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.07.2025 20:06, dmkhn@xxxxxxxxx wrote:
> On Wed, Jul 30, 2025 at 07:35:04AM +0200, Jan Beulich wrote:
>> On 30.07.2025 00:18, dmkhn@xxxxxxxxx wrote:
>>> On Mon, Jul 28, 2025 at 11:32:43AM +0200, Jan Beulich wrote:
>>>> On 26.07.2025 11:20, Julien Grall wrote:
>>>>> On 25/07/2025 22:24, dmkhn@xxxxxxxxx wrote:
>>>>>> From: Denis Mukhin <dmukhin@xxxxxxxx>
>>>>>>
>>>>>> __printk_ratelimit() is never used outside of the console driver.
>>>>>> Remove it from the lib.h and merge with the public printk_ratelimit().
>>>>>
>>>>> Is this solving any sort of violation? Asking because even if the
>>>>> function is only used by one caller, I could see a benefit to be able to
>>>>> use different value for the ratelimit. So I leaning towards keep the
>>>>> code as-is.
>>>>
>>>> +1
>>>>
>>>> In fact I'm surprised (or maybe not) that we still don't make better use
>>>> the rate limiting functionality.
>>>
>>> Out of curiosity, do you have any ideas re: make better use of the rate
>>> limiting functionality?
>>
>> No concrete ones; thinking about this has been way too long ago.
>>
>>> Build-time parameterization?
>>
>> That and/or command line controls.
> 
> Got it.
> 
> Can you please explain why exporting __printk_ratelimit() is still required
> for implementation of build/command line settings in console.c?

I didn't say console.c, did I? Whatever subsystem wanted to do proper rate
limiting would need to gain some way of controlling this (as said, build
time or cmdline driven), and it'll then need that function: How would it
effect the behavior with custom ms and/or burst values, without having
that function to call? (It is another thing that the function, using static
variables rather than per-caller state, may not be quite ready for that
kind of use. Also the arbitrary and hard-coded 10 * 5 * 1000 there would
probably also want to be customizable.)

What you may want to do for Misra's sake is make the function static for
the time being. The compiler will then fold it into its sole caller,
until some new user appears. (At that occasion dropping one of the
underscores may also be reasonable.)

Jan