Bug 1191122

Summary: ntpd -x steps clock on leap second
Product: Red Hat Enterprise Linux 7 Reporter: Miroslav Lichvar <mlichvar>
Component: ntpAssignee: Miroslav Lichvar <mlichvar>
Status: CLOSED ERRATA QA Contact: Jakub Prokes <jprokes>
Severity: high Docs Contact:
Priority: urgent    
Version: 7.1CC: chorn, fkrska, hmatsumo, jkurik, john.haxby, jprokes, jscalf, kabbott, michele, mlichvar, mschuppe, ovasik, psklenar, rrajaram, vanhoof
Target Milestone: rcKeywords: ZStream
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: ntp-4.2.6p5-20.el7 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: 1190619
: 1214752 (view as bug list) Environment:
Last Closed: 2015-11-19 08:38:15 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1110700, 1133060, 1191021, 1205796, 1214752    

Description Miroslav Lichvar 2015-02-10 13:47:08 UTC 
+++ This bug was initially created as a clone of Bug #1190619 +++

Description of problem:
With older ntp versions, the -x option was sometimes used as a workaround to avoid kernel inserting/deleting leap seconds by stepping the clock and possibly upsetting running applications. That no longer works with 4.2.6 as ntpd steps the clock itself when a leap second occurs.

The fix is to treat the one second offset gained during leap second as a normal offset and check the stepping threshold (set by -x or tinker step) to decide if a step should be applied.

Version-Release number of selected component (if applicable):
ntp-4.2.6p5

How reproducible:
Always

Steps to Reproduce:
1. add -x to /etc/sysconfig/ntpd
2. wait for leap second
3. observe how was clock corrected

Actual results:
step

Expected results:
slew
Comment 18 errata-xmlrpc 2015-11-19 08:38:15 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2015-2231.html