Bug 42475 – sysvol sync: lock is not released if process is killed

Bug 42475 - sysvol sync: lock is not released if process is killed


Summary:	sysvol sync: lock is not released if process is killed

Status:	CLOSED FIXED

Product:	UCS
Classification:	Unclassified
Component:	Samba4
Version:	UCS 4.1
Hardware:	Other Linux

Importance:	P5 normal (vote)
Target Milestone:	UCS 4.1-3-errata
Assigned To:	Felix Botner
QA Contact:	Arvid Requate

URL:
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Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2016-09-22 14:00 CEST by Felix Botner
Modified:	2016-10-20 12:40 CEST (History)
CC List:	0 users

See Also:
What kind of report is it?:	Bug Report
What type of bug is this?:	5: Major Usability: Impairs usability in key scenarios
Who will be affected by this bug?:	3: Will affect average number of installed domains
How will those affected feel about the bug?:	2: A Pain – users won’t like this once they notice it
User Pain:	0.171
Enterprise Customer affected?:
School Customer affected?:	Yes
ISV affected?:
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Description Felix Botner

2016-09-22 14:00:22 CEST

Stop cron
/etc/init.d/cron stop

Added "sleep 1000" to /usr/share/univention-samba4/scripts/sysvol-sync.sh after "flock -n 9 || exit 0" line.

Start script
bash -x /usr/share/univention-samba4/scripts/sysvol-sync.sh

Kill both sysvol-sync.sh processes
kill 563 565

Restart script

-> bash -x /usr/share/univention-samba4/scripts/sysvol-sync.sh
+ . /usr/share/univention-lib/ucr.sh
++ /usr/sbin/univention-config-registry shell hostname samba4/sysvol/sync/host
+ eval hostname=master
++ hostname=master
+ DEBUG=false
+ SYSVOL_PATH=/var/lib/samba/sysvol
+ SYSVOL_SYNCDIR=/var/cache/univention-samba4/sysvol-sync
+ SYSVOL_SYNC_TRIGGERDIR=/var/cache/univention-samba4/sysvol-sync/.trigger
+ PROCESS_LOCKFILE=/var/lock/sysvol-sync-process
+ SYSVOL_LOCKFILE=/var/lock/sysvol-sync-dir
+ LC_ALL=C
+ flock -n 9
+ exit 0

Now flock can't get the lock and immediately exists


Problem seems to be the missing flock -u

       -u, --unlock
              Drop  a  lock.  This is usually not required, since a lock is automatically dropped when the file is closed.  However, it may be required in
              special cases, for example if the enclosed command group may have forked a background process which should not be holding the lock.

Replacing "flock -n 9 || exit 0" with "flock -un 9 || exit 0" works for me

Comment 1 Felix Botner

2016-09-22 14:19:30 CEST

fixed in univention-samba4 (72750) in errata4.1-3, merged to 4.2-0

univention-samba4.yaml

Comment 2 Stefan Gohmann

2016-09-23 06:29:13 CEST

Please check the YAML file: http://jenkins.knut.univention.de:8080/job/UCS-4.1/job/UCS-4.1-3/job/ErrataValidation/lastCompletedBuild/testReport/

Comment 3 Felix Botner

2016-09-23 14:26:12 CEST

(In reply to Stefan Gohmann from comment #2)
> Please check the YAML file:
> http://jenkins.knut.univention.de:8080/job/UCS-4.1/job/UCS-4.1-3/job/
> ErrataValidation/lastCompletedBuild/testReport/

fixed (univention-samba in yaml instead of univention-samba4)

Also had to fix debian/rules (split override_dh_fixperms into override_dh_fixperms and override_dh_fixperms-indep), as we no longer build the all packages on amd64.

Comment 4 Arvid Requate

2016-10-17 16:51:48 CEST

Ok, works and the advisory is ok.

Comment 5 Janek Walkenhorst

2016-10-20 12:40:40 CEST

<http://errata.software-univention.de/ucs/4.1/309.html>