From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cyril Hrubis <chrubis@suse.cz>
Date: Thu, 7 Jan 2021 14:57:44 +0100
Subject: [LTP] [PATCH 2/3] lib: implement rtctime_save and
 rtctime_restore function
In-Reply-To: <20201223033517.1464263-3-gengcixi@gmail.com>
References: <20201223033517.1464263-1-gengcixi@gmail.com>
 <20201223033517.1464263-3-gengcixi@gmail.com>
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>  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.

> +	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