group.of.nepali.translators team mailing list archive

[Robie Basak <1706818@xxxxxxxxxxxxxxxxxx>]

Thank you for taking the time to report this bug and helping to make
Ubuntu better.

I've confirmed that the issue is as you describe in Xenial. Trusty pre-
dates the change to locking in ntp.if-up, so is consistent. Zesty is
also consistent in using flock in both places, as is Artful. So this bug
affects only Xenial.

In order to understand the importance of this bug, please could you
explain why you're using both ntp and ntpdate? ntpdate isn't installed
by default on Xenial, and shouldn't be required in the normal case
because ntp defaults to "-g". So you could work around this bug by just
removing the ntpdate package. Is there a particular reason that this
won't work in your case?

** Also affects: ntp (Ubuntu Xenial)
   Importance: Undecided
       Status: New

** Changed in: ntp (Ubuntu)
       Status: New => Fix Released

** Changed in: ntp (Ubuntu Xenial)
       Status: New => Triaged

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https://bugs.launchpad.net/bugs/1706818

Title:
  mismatched file locking since 1:4.2.8p4+dfsg-3ubuntu1 causes race
  leaving ntp dead on reboot

Status in ntp package in Ubuntu:
  Fix Released
Status in ntp source package in Xenial:
  Triaged
Status in ntp package in Debian:
  Unknown

Bug description:
  ntpdate and ntp conflict on the NTP well-known-socket. If ntp and
  ntpdate 1:4.2.8p4+dfsg-3ubuntu5.5 are installed on Xenial, and there
  are 2 static interfaces configured, most often we find that ntpd is
  not running after a reboot.

  When the ntp service is started by systemd, ntp fails to bind the NTP
  socket because ntpdate is running in the background. It's intended
  that ntp and ntpdate try to avoid this conflict with a lock file, but
  the locking mechanism was changed in ntpdate.if-up (from lockfile to
  flock), but it was not changed in ntp.init. Previously the file
  locking prevented ntp from trying to start when ntpdate was running.
  Not any more.

  Having multiple interfaces causes a much longer period of the socket
  being unavailable, because the 2 ntpdate processes will get serialized
  by the lock, while the ntp service is looking for a different lock, so
  it just plows right in.  Attempts by netdate.if-up to stop and start
  ntp seem to overlap and when the final start is invoked, systemd seems
  to thing ntp is already running, though it has failed.

  In 1:4.2.8p4+dfsg-3ubuntu1 the following change was made:
    debian/ntpdate.if-up: Drop lockfile mechanism as upstream is using flock now.
  Looks like corresponds to rev 371 of debian/ntpdate.if-up from upstream.

  This change diverged locking between ntpdate.if-up and ntp.init. This
  was rectified in rev 451 of ntp.init, to use compatible locking, but
  that doesn't appear in the Ubuntu version.

  
  System Information:

   lsb_release -rd:
     Description:    Ubuntu 16.04.2 LTS
     Release:        16.04

  
   apt-cache policy ntpdate:

     ntpdate:
       Installed: 1:4.2.8p4+dfsg-3ubuntu5.5
       Candidate: 1:4.2.8p4+dfsg-3ubuntu5.5
       Version table:
      *** 1:4.2.8p4+dfsg-3ubuntu5.5 100
             100 /var/lib/dpkg/status

   apt-cache policy ntp:

     ntp:
       Installed: 1:4.2.8p4+dfsg-3ubuntu5.5
       Candidate: 1:4.2.8p4+dfsg-3ubuntu5.5
       Version table:
      *** 1:4.2.8p4+dfsg-3ubuntu5.5 100
             100 /var/lib/dpkg/status

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