[Devel] [PATCH rh7] ve: Add interface for @start_timespec and @real_start_timespec adjustmen

[Andrey Vagin]

On Tue, Feb 09, 2016 at 01:02:09PM +0300, Vladimir Davydov wrote:
> On Mon, Feb 08, 2016 at 11:32:12AM +0300, Cyrill Gorcunov wrote:
> > +static int ve_ts_read(struct cgroup *cg, struct cftype *cft, struct seq_file *m)
> > +{
> > +	struct ve_struct *ve = cgroup_ve(cg);
> > +	struct timespec ts, *delta;
> > +
> > +	do_posix_clock_monotonic_gettime(&ts);
> > +	if (cft->private == VE_CF_START_TIMESPEC) {
> > +		delta = &ve->start_timespec;
> > +	} else if (cft->private == VE_CF_REAL_START_TIMESPEC) {
> > +		delta = &ve->real_start_timespec;
> > +		monotonic_to_bootbased(&ts);
> > +	} else {
> > +		delta = &ts;
> > +		memset(&ts, 0, sizeof(ts));
> > +		WARN_ON_ONCE(1);
> > +	}
> > +
> > +	set_normalized_timespec(&ts, ts.tv_sec - delta->tv_sec,
> > +				ts.tv_nsec - delta->tv_nsec);
> > +	seq_printf(m, "%ld %ld", ts.tv_sec, ts.tv_nsec);
> > +	return 0;
> > +}
> 
> So the output of ve.start_timespec is going to evolve over time, right?
> This looks weird to me. Wouldn't it be better if we returned the
> timespec as is?
>

The idea is that we can read the content of these files and write them back
on the another host to restore "a time namespace".