Re: [chrony-users] Chronyd unexpected abort after server was set to "online"

[Arndt Kritzner <kritzner@xxxxxxxxxxx>]

Miroslav, thanks for your quick answer. With your suggested modifications applied I get this log output:

~ # chronyd -d -d
main.c:355:(main)[16-12:44:24] chronyd version 1.29.1 starting
sys_linux.c:1022:(get_version_specific_details)[16-12:44:25] Linux kernel major=3 minor=4 patch=93
sys_linux.c:1080:(get_version_specific_details)[16-12:44:25] hz=100 shift_hz=7 freq_scale=1.00000000 nominal_tick=10000
slew_delta_tick=833 max_tick_bias=1000 shift_pll=2
reference.c:194:(REF_Initialise)[16-12:44:25] Initial frequency -83300.000 ppm
acquire.c:699:(process_measurements)[16-12:44:25] System's initial offset : 946.636438 seconds fast of true (step)
ntp_core.c:1575:(NCR_TakeSourceOnline)[16-12:31:14] Source 148.251.9.60 online
sourcestats.c:345:(find_best_sample_index)[16-12:31:15] n=1 i=0 best=-1 elapsed=-0.000000e+00
chronyd: sourcestats.c: 346: find_best_sample_index: Assertion `elapsed >= 0.0' failed.
Aborted
~ #

Kind regards
Arndt

Am 16.06.2014 12:07, schrieb Miroslav Lichvar:
> On Mon, Jun 16, 2014 at 11:34:16AM +0200, Arndt Kritzner wrote:
>> Hi,
>>
>> we are using chrony on a device with AVR32 CPU since a while and this seemed to work. Bu today I checked the function
>> and experienced, that chronyd always aborts, after servers became online. Chronyd start looks normal:
>>
>> ~ # chronyd -R -d
>> main.c:355:(main)[13-13:50:51] chronyd version 1.29 starting
>> sys_linux.c:1022:(get_version_specific_details)[13-13:50:51] Linux kernel major=3 minor=4 patch=77
>> sys_linux.c:1080:(get_version_specific_details)[13-13:50:51] hz=100 shift_hz=7 freq_scale=1.00000000 nominal_tick=10000
>> slew_delta_tick=833 max_tick_bias=1000 shift_pll=2
>>
>> But after setting servers to "online" through chronyc chronyd closes:
>>
>> ntp_core.c:1575:(NCR_TakeSourceOnline)[13-13:51:42] Source 176.9.1.148 online
>> chronyd: sourcestats.c: 345: find_best_sample_index: Assertion `elapsed >= 0.0' failed.
>> Aborted
>> ~ #
> 
> Hm, that's interesting. Can you get a backtrace for this crash or get
> chronyd output with this patch, so we can see the value of elapsed and
> the number of samples?
> 
> --- a/sourcestats.c
> +++ b/sourcestats.c
> @@ -342,6 +342,7 @@ find_best_sample_index(SST_Stats inst, double *times_back)
>      j = get_buf_index(inst, i);
>  
>      elapsed = -times_back[i];
> +    LOG(LOGS_INFO, LOGF_SourceStats, "n=%d i=%d best=%d elapsed=%e", inst->n_samples, i, best_index, elapsed);
>      assert(elapsed >= 0.0);
>  
>      root_distance = inst->root_dispersions[j] + elapsed * inst->skew + 0.5 * inst->root_delays[j];
> 
> I guess this is also present in the latest 1.30-pre1, it might help us
> to see the complete output of "chronyd -d -d" when compiled with
> --enable-debug.
> 
>> /etc/chrony.conf:
>> server pool.ntp.org offline
>> refclock SHM 0 offset 0.0 delay 0.2 refid GPS
>> refclock SHM 1 offset 0.0 delay 0.0 refid PPS
>> refclock SOCK /tmp/chrony.ttyS3.sock
>> driftfile /etc/chrony.drift
>> keyfile /etc/chrony.keys
>> commandkey 1
>> makestep 1000 10
>> initstepslew 30 pool.ntp.org
> 
> The config looks ok to me.
> 
>> Any explanations for this behaviour? And any clue to solve it? The internet connection does not exist permanently and
>> switches between LAN and cellphone network. That's the reason we use "offline"/"online" switching.
> 
> I think in older versions this could happen when something other than
> chronyd stepped the system clock back and an "out of order" sample was
> accumulated in chronyd. A check for that was added in 1.27, so it
> shouldn't happen with 1.29. This looks like another bug and it needs
> to be fixed.
> 
> Thanks for the report.
> 

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