Re: [Patch v3 7/7] sched: thermal: Enable tuning of decay period

Quentin Perret
2019-10-15T10:15:00Z

Hi Thara,

On Sunday 13 Oct 2019 at 20:58:25 (-0400), Thara Gopinath wrote:
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 00fcea2..5056c08 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -376,6 +376,13 @@ static struct ctl_table kern_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec,
> },
> + {
> + .procname = "sched_thermal_decay_coeff",
> + .data = &sysctl_sched_thermal_decay_coeff,
> + .maxlen = sizeof(unsigned int),
> + .mode = 0644,
> + .proc_handler = proc_dointvec,

Perhaps change this for 'sched_proc_update_handler' with min and max
values ? Otherwise userspace is allowed to write nonsensical values
here. And since sysctl_sched_thermal_decay_coeff is used to shift, this
can lead to an undefined behaviour.

Also, could we take this sysctl out of SCHED_DEBUG ? I expect this to be
used/tuned on production devices where SCHED_DEBUG should theoretically
be off.

Thanks,
Quentin