Re: [tip:sched/core] sched/cputime: Refactor the cputime_adjust() code

[Rik van Riel]

On Fri, 2017-06-30 at 06:10 -0700, tip-bot for Gustavo A. R. Silva
wrote:

> +++ b/kernel/sched/cputime.c
> @@ -615,19 +615,13 @@ static void cputime_adjust(struct task_cputime
> *curr,
> Â	Â* userspace. Once a task gets some ticks, the monotonicy
> code at
> Â	Â* 'update' will ensure things converge to the observed
> ratio.
> Â	Â*/
> -	if (stime == 0) {
> -		utime = rtime;
> -		goto update;
> +	if (stime != 0) {
> +		if (utime == 0)
> +			stime = rtime;
> +		else
> +			stime = scale_stime(stime, rtime, stime +
> utime);
> Â	}
> Â
> -	if (utime == 0) {
> -		stime = rtime;
> -		goto update;
> -	}
> -
> -	stime = scale_stime(stime, rtime, stime + utime);
> -
> -update:

Wait, what?

This get rid of the utime = rtime assignment, when
stime == 0.  That could be a correctness issue.

> Â	/*
> Â	Â* Make sure stime doesn't go backwards; this preserves
> monotonicity
> Â	Â* for utime because rtime is monotonic.