Re: [PATCH] panic: only warn about deprecated panic_print on write access

[Gal Pressman <gal@nvidia.com>]

On 08/01/2026 17:52, Petr Mladek wrote:
> On Wed 2026-01-07 15:20:44, Feng Tang wrote:
>> On Wed, Jan 07, 2026 at 08:41:22AM +0200, Gal Pressman wrote:
>>> On 07/01/2026 5:00, Feng Tang wrote:
>>>>> @@ -1014,7 +1015,6 @@ static int panic_print_set(const char *val, const struct kernel_param *kp)
>>>>>  
>>>>>  static int panic_print_get(char *val, const struct kernel_param *kp)
>>>>>  {
>>>>> -	panic_print_deprecated();
>>>>
>>>> Actually this was intentional, in one of the patch version, this
>>>> panic_print_get() was not there but reusing the param_get_ulong().
>>>>
>>>> It was added later as sometimes developer do want to runtime check
>>>> the current 'panic_print' setting through /sys/module/kernel/parameters/
>>>> interface, and I thought it may be better to give the warning.
>>>
>>> I figured it would make sense to keep the behaviors consistent.
> 
> I see.
> 
>> When people run 'sysctl -a', in 99.9% cases, the users don't care
>> 'panic_print' or even don't know what 'panic_print' is, that's why
>> I think removing it makes sense.
>>
>> But for a user running 'cat /sys/module/kernel/parameters/panic_rint',
>> giving a warning is meaningful.
> 
> Makes perfect sense.
> 
> We need to make people aware that "panic_print" will eventually go
> away. 'sysctl -a' is different because it prints all values and
> there is big chance that the caller is not interested in "panic_print"
> at all.
> 
> It makes sense to remove the warning from sysctl read. But I would
> keep it in sysfs read.

The sysfs entry exhibits the same issue, just different command:

# systool -m kernel -v

Or:

# grep . /sys/module/kernel/parameters/*