Re: [PATCH] tick/sched: check skew_tick kernel parameter's validity

[Thomas Gleixner]

On Wed, Sep 30 2026 at 22:01, Sergey Shtylyov wrote:
> On 9/29/26 11:01 PM, Thomas Gleixner wrote:
> [...]>> In skew_tick(), the result of get_option() call is ignored, so even if a
>>> value of the skew_tick kernel parameter was not specified (or specified
>>> as a list or range), the kernel won't complain. Add the missing check...
>>>
>>> Found by Linux Verification Center (linuxtesting.org) with the Svace static
>>> analysis tool.
>>>
>>> Signed-off-by: Sergey Shtylyov <s.shtylyov@xxxxxxxxxxxx>
>>>
>>> ---
>>> The patch is against the timers/nohz branch of the tip.git repo...
>>>
>>>  kernel/time/tick-sched.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
>>> index c1ee0b256445..34ceccdd49b5 100644
>>> --- a/kernel/time/tick-sched.c
>>> +++ b/kernel/time/tick-sched.c
>>> @@ -1483,7 +1483,8 @@ static int sched_skew_tick;
>>>
>>>  static int __init skew_tick(char *str)
>>>  {
>>> -     get_option(&str, &sched_skew_tick);
>>> +     if (get_option(&str, &sched_skew_tick) != 1)
>>> +             return -EINVAL;
>>>
>>>       return 0;
>>>  }
>> 
>> sched_skew_tick should be converted to bool and this function should
>> simply do:
>> 
>>        return kstrtobool(str, &sched_skew_tick);
>
>    Thanks for your comment!
>    OK, I'll do that (and add the Suggested-by: tag, of/c)...
>
>> And to make it complete, sched_skew_tick should be annotated with
>> ro_after_init.
>
>    I guess you meant __ro_after_init? Would it then be OK adding it
> in the same patch?

As you change the data type of the variable anyway that's fine. Just
mention it in the changelog.

Thanks,

        tglx