[LTP] [PATCH 2/3] lib: implement rtctime_save and rtctime_restore function

[Cixi Geng]

Cyril Hrubis <chrubis@suse.cz> 于2021年1月7日周四 下午9:56写道：
>
> >  static struct timespec real_begin, mono_begin;
> >
> > +static struct rtc_time rtc_begin;
> > +
> >  static int clock_saved;
> >
> >  void tst_wallclock_save(void)
> > @@ -58,3 +61,42 @@ void tst_wallclock_restore(void)
> >       if (tst_clock_settime(CLOCK_REALTIME, &adjust))
> >               tst_brk(TBROK | TERRNO, "tst_clock_settime() realtime failed");
> >  }
> > +
> > +void tst_rtctime_save(void)
> > +{
> > +     /* save initial monotonic time to restore it when needed */
> > +     if (tst_rtc_gettime(&rtc_begin))
> > +             tst_brk(TBROK | TERRNO, "tst_rtc_gettime() realtime failed");
> > +
> > +     if (tst_clock_gettime(CLOCK_MONOTONIC_RAW, &mono_begin))
> > +             tst_brk(TBROK | TERRNO, "tst_clock_gettime() monotonic failed");
> > +
> > +     clock_saved = 1;
>
> It would be better if we defined rtc_clock_saved for the rtc* functions
> instead.
>
> > +}
> > +
> > +void tst_rtctime_restore(void)
> > +{
> > +     static struct timespec mono_end, elapsed;
> > +     static struct timespec rtc_begin_tm, rtc_adjust;
> > +     static struct rtc_time rtc_restore;
> > +
> > +     if (!clock_saved)
> > +             return;
> > +
> > +     clock_saved = 0;
> > +
> > +     if (tst_clock_gettime(CLOCK_MONOTONIC_RAW, &mono_end))
> > +             tst_brk(TBROK | TERRNO, "tst_clock_gettime() monotonic failed");
> > +
> > +     elapsed = tst_timespec_diff(mono_end, mono_begin);
> > +
> > +     rtc_begin_tm.tv_sec = tst_rtc_tm_to_time(&rtc_begin);
>
> We should clear the tv_nsec here otherwise it will contain garbage.
The rtc_begin_tm is defined in this function， and tv_nsec never assigned，
so I think it will not produce any garbage.
>
> > +     rtc_adjust = tst_timespec_add(rtc_begin_tm, elapsed);
> > +
> > +     tst_rtc_time_to_tm(rtc_adjust.tv_sec, &rtc_restore);
> > +
> > +     /* restore realtime clock based on monotonic delta */
> > +     if (tst_rtc_settime(&rtc_restore))
> > +             tst_brk(TBROK | TERRNO, "tst_rtc_settime() realtime failed");
> > +}
>
> Other than this, it looks good.
>
> --
> Cyril Hrubis
> chrubis@suse.cz