ntpq change in behaviour

[Eric S. Raymond]

Achim Gratz via devel <devel at ntpsec.org>:
> Eric S. Raymond via devel writes:
> > Well, shit.  Achim, have you IDed an actual bug, or is that a guess based
> > on the timing of the report?
> 
> No, I've updated two boxes yesterday and they've reported a loop
> frequency of essentially (but not exactly) zero since.  Something is
> still keeping the clock on track (kernel PLL?), but less accurate than
> normal.  PLL state is randomly reported as synced and unsynced.
> Reverted back to before the lockclock change and they are snapping back
> to normal.
> 
> I have no teyeballed something that jumps out at me, but I notice that
> lockclock is never actively initialized.  Since it's defined as a
> static, I'm not sure the compiler puts that in for you.

C is in fact supposed to zero uninitialized statics.

But it sounds like there's some other bug.  Can't say I'm overly surprised;
the loopfilter code has a long history of being fiendishly fragile, I knew
this change was risky.

Your report puts me in a bad spot. You obviously know how to tell when
it's busted, but I don't. This is one of those times we get bitten by
the fact that my knowledge of NTP operation from the outside is still
very weak. In effect, I can't test the change myself - I don't know
enough about what "normal" looks like from outside the code.

I can of course just revert the change, but there's an actual reason for
it.  We've (a) had a report of a distro maker setting ENABLE_LOCKCLOCK
on, disabling time sync, and (b) we want to not potentially cheese off
NIST by removing the support.  Thus, the attempt to change it to a runtime
option.

Therefore...would you please take a hard look at the change and see if
you can repair it?  I hate to slough off my mistakes on anybody, but the
fix needs to be applied by somebody who can test it.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

My work is funded by the Internet Civil Engineering Institute: https://icei.org
Please visit their site and donate: the civilization you save might be your own.