On Mon, 2015-06-29 at 17:28 +0200, Fredrik Markström wrote:
> Hello Peter, the locking part looks good, I don't have a strong
> opinion on per task/signal lock vs global lock.
>
> But with the patch we still update prev->utime and prev->stime
> independently, which was the original problem. But maybe the locking
> and monoticity/sum issue should be addressed by two separate patches
> since they are separate bugs ?
>
> The part I'm referring to is the change below from my original patch
> (maybe without the WARN_ON:s ?):
>
> …
> - cputime_advance(&prev->stime, stime);
> - cputime_advance(&prev->utime, utime);
> + if (stime < prev->stime) {
> + stime = prev->stime;
> + utime = rtime - stime;
> + } else if (utime < prev->utime) {
> + utime = prev->utime;
> + stime = rtime - utime;
> + }
> + WARN_ON(stime < prev->stime);
> + WARN_ON(utime < prev->utime);
> + WARN_ON(stime + utime != rtime);
How about substituting:
prev->stime = max(prev->stime, stime);
prev->utime = max(prev->utime, utime);
with
if (stime > prev->stime || utime > prev->utime) {
prev->stime = stime;
prev->utime = utime;
}
in Peter's patch?
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