Re: [PATCH] time, ntp: Do not update time_state in middle of leap second [v3]

From: Prarit Bhargava
Date: Fri Feb 20 2015 - 09:15:51 EST




On 02/19/2015 12:00 PM, Jiri Bohac wrote:
> Hi,
>
> I'm trying to understand what exactly is going on here...
>
> On Thu, Feb 12, 2015 at 08:58:19AM -0500, Prarit Bhargava wrote:
>> The test did the following in userspace:
>>
>> tx.modes = ADJ_STATUS;
>> tx.status = STA_INS;
>>
>> /* send leap second request */
>> ret = adjtimex(&tx);
>>
>> /* Check adjtimex output every half second */
>> now = tx.time.tv_sec;
>> while (now < next_leap+2) {
>> char buf[26];
>> ret = adjtimex(&tx);
>>
>> ctime_r(&tx.time.tv_sec, buf);
>> buf[strlen(buf)-1] = 0; /*remove trailing\n */
>>
>> printf("%s + %6ld us\t%s\n",
>> buf,
>> tx.time.tv_usec,
>> time_state_str(ret));
>> now = tx.time.tv_sec;
>> /* Sleep for another half second */
>> ts.tv_sec = 0;
>> ts.tv_nsec = NSEC_PER_SEC/2;
>> clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL);
>> }
>>
>> After some investigation it was noted that the test contained a small error:
>> the test does not reinitialize tx.status and reissues the STA_INS every
>> 1/2 second.
>
> Prarit, can you explain who sets the STA_PLL flag, so that
> process_adj_status() detects a STA_PLL->!STA_PLL transition and
> goes to the branch that sets time_state = TIME_OK?

Jiri,

The test being run is:

https://github.com/johnstultz-work/timetests/blob/master/leap-a-day.c

prior to commit

https://github.com/johnstultz-work/timetests/commit/be4526e8b5d48cd108a8d2cf7f5c8fd763acf421

>
> Is that ntpd running in parallel with your test program? If that

No -- ntpd is disabled (chronyd in the case of systemd + current Fedora).

P.
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