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-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to ntp in Ubuntu. 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: Fix Released Status in ntp source package in Zesty: Fix Released Status in ntp source package in Artful: Fix Released Status in ntp package in Debian: Fix Released Bug description: [Impact] * The locks of ntpdate the ifup hook and the ntp service start do not match, therefore installation of ntpdate can harmstring the start of ntp at boot. * The change ports back what Debian added later and we merged in Zesty. It does two things: 1. it makes the lock paths actually match 2. it drops the usage of lockfile-progs which never was a dependency and uses flock directly. [Test Case] * Prep - Taking a Xenial VM (to avoid all the time set rejects in a container from cluttering the view) - Installing ntp - Check status of ntp - Reboot the VM - Check status of ntp # Until now all should be good * Break it - install ntpdate - reboot - Check status of ntp - It (likely) is failed for "blocked known address being busy" - This is somewhat of a race, adding more extra network devices in libvirt to your guest increases the chance if you can't reproduce. * Fix it - install the fix from proposed (or the ppa in c#14) - reboot - ntp is now running correctly after reboot [Regression Potential] * It was locking before as well, just on a lock never contended and potentially failing to have the lockfile-progs calls available. Due to the change the init now of ntp can take longer (until the ntpdate calls are out of the way) * For a fallback in case locking goes crazy in unexpected ways the timeout of the flock (180s) is intentionally not checked for bad return codes. That way in those cases ntp still tries to initialize and if it fails for an ntpdate blocking the port it didn't "loose" anything by being stalled. Therefor I'd consider that the actual regression potential rather low and safe. [Other Info] * This is kind of a bug-zombie, fixed in zesty but resurrected in Debian (and Ubuntu by our merge) due to the addition of a native systemd service. Now that Dev is finally (again) good it is time to tackle the Xenial SRU. --- 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ntp/+bug/1706818/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
