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Bug 1244649

Summary: iothreadadd will create a new iothread in xml which will disappear after restart libvirtd
Product: Red Hat Enterprise Linux 7 Reporter: Luyao Huang <lhuang>
Component: libvirtAssignee: John Ferlan <jferlan>
Status: CLOSED DUPLICATE QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.2CC: dyuan, honzhang, mzhan, rbalakri
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2015-08-12 12:21:14 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:

Description Luyao Huang 2015-07-20 08:29:15 UTC 
Description of problem:
iothreadadd will leave a new iothread even create it failed

Version-Release number of selected component (if applicable):
libvirt-1.2.17-2.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. find a way to make iothreadadd get failed after do it success in qemu side
i chose use iothreadadd when cpuset (although this is a another issue):

# vim /etc/libvirt/qemu.conf
cgroup_controllers = [ "devices", "blkio", "cpu", "cpuacct", "memory"]

# virsh start test4
Domain test4 started

# virsh iothreadinfo test4
 IOThread ID     CPU Affinity   
---------------------------------------------------
 1               0
 2               1


2. add an iothread

# virsh iothreadadd test4 3
error: Requested operation is not valid: failed to set cpuset.cpus in cgroup for id 3

# echo $?
1


3. although iothread return error, but we still show it in iothreadinfo

# virsh iothreadinfo test4
 IOThread ID     CPU Affinity   
---------------------------------------------------
 1               0
 2               1
 3               1


Actual results:
iothreadadd will leave a new iothread even create it failed

Expected results:
return success and print this error in the log, or remove the new create iothread if we get failed in cgroup or set task part (this will be more safe then just print the error in the log)

Additional info:
Comment 1 Luyao Huang 2015-07-20 08:57:38 UTC 
Also i notice this won't save the change to status file, which will make it disappear after restart libvirt:

# virsh iothreadadd test4 5
error: Requested operation is not valid: failed to set cpuset.cpus in cgroup for id 5

# virsh iothreadinfo test4
 IOThread ID     CPU Affinity   
---------------------------------------------------
 1               0
 2               1
 4               1
 5               1


# virsh dumpxml test4 |grep "iothreads"
  <iothreads>4</iothreads>
[root@lhuang ~]# virsh dumpxml test4 |grep "iothread"
  <iothreads>4</iothreads>
  <iothreadids>
    <iothread id='4'/>
    <iothread id='5'/>
  </iothreadids>
    <iothreadpin iothread='1' cpuset='0'/>
    <iothreadpin iothread='2' cpuset='1'/>


# service libvirtd restart
Redirecting to /bin/systemctl restart  libvirtd.service


# virsh dumpxml test4 |grep "iothread"
  <iothreads>3</iothreads>
  <iothreadids>
    <iothread id='4'/>
  </iothreadids>
    <iothreadpin iothread='1' cpuset='0'/>
    <iothreadpin iothread='2' cpuset='1'/>

# virsh iothreadadd test4 6
error: internal error: got wrong number of IOThread ids from QEMU monitor. got 5, wanted 4

# virsh iothreadpin test4 6 1
error: invalid argument: iothread 6 not found

# virsh iothreadadd test4 6
error: internal error: unable to execute QEMU command 'object-add': attempt to add duplicate property 'iothread6' to object (type 'container')
Comment 2 Luyao Huang 2015-07-20 09:35:20 UTC 
Sorry for forget past the xml in commant 0, getinfo can see it is not a bug here, but comment 1 is the main issue here.
Comment 3 John Ferlan 2015-08-12 12:21:14 UTC 

*** This bug has been marked as a duplicate of bug 1244664 ***