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

[Thomas Gleixner]

On Sat, Aug 29 2026 at 23:25, Sergey Shtylyov 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);

And to make it complete, sched_skew_tick should be annotated with
ro_after_init.

Thanks,

        tglx