Re: [LTP] [PATCH] sched/rt: Disallow writing invalid values to sched_rt_period_us

[Cyril Hrubis]

Hi!
> Documentation/scheduller/sched-rt-group.rst [1] specifies this as values from -1 to
> (INT_MAX - 1), I guess due int range. Looking into proc_dointvec_minmax() [2]
> even INT_MAX would pass the check. I suppose we can do nothing about that,
> because there is no value in sysctl_vals[] which would represent INT_MAX - 1.
> 
> And you specify in LTP test range: from -1 to INT_MAX.
> 
> But even much shorter value than INT_MAX fails:
> 
> $ echo 1234567 > /proc/sys/kernel/sched_rt_runtime_us
> sh: echo: write error: Invalid argument

That is because runtime_us must be < period_us by definition, since
runtime_us defines how much time is allocated from the period_us. I
guess that this is not described good enough in the kernel docs.

-- 
Cyril Hrubis
chrubis@xxxxxxx