[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.
> 
> Mind adding a second patch to your series, clarifying 
> Documentation/scheduler/sched-rt-group.rst?

Yes, that is the plan. I've been working on LTP release for past two
weeks so this has been postponed. I will get to it hopefully next week.

-- 
Cyril Hrubis
chrubis@suse.cz