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qemu-iotests: fix 203 migration completion race

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There is a race between the test's 'query-migrate' QMP command after the
QMP 'STOP' event and completing the migration:

The test case invokes 'query-migrate' upon receiving 'STOP'.  At this
point the migration thread may still be in the process of completing.
Therefore 'query-migrate' can return 'status': 'active' for a brief
window of time instead of 'status': 'completed'.  This results in
qemu-iotests 203 hanging.

Solve the race by enabling the 'events' migration capability, which
causes QEMU to emit migration-specific QMP events that do not suffer
from this race condition.  Wait for the QMP 'MIGRATION' event with
'status': 'completed'.

Reported-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20180305155926.25858-1-stefanha@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2018-03-05 15:59:26 +00:00 committed by Max Reitz
parent 39eaefcedb
commit 21794244d4
2 changed files with 16 additions and 4 deletions
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15
tests/qemu-iotests/203
View file

@ -49,11 +49,18 @@ with iotests.FilePath('disk0.img') as disk0_img_path, \
node_name='drive1-node', iothread='iothread0',
force=True))
iotests.log('Enabling migration QMP events...')
iotests.log(vm.qmp('migrate-set-capabilities', capabilities=[
{
'capability': 'events',
'state': True
}
]))
iotests.log('Starting migration...')
iotests.log(vm.qmp('migrate', uri='exec:cat >/dev/null'))
while True:
vm.get_qmp_event(wait=60.0)
result = vm.qmp('query-migrate')
status = result.get('return', {}).get('status', None)
if status == 'completed':
event = vm.event_wait('MIGRATION')
iotests.log(event, filters=[iotests.filter_qmp_event])
if event['data']['status'] == 'completed':
break

5
tests/qemu-iotests/203.out
View file

@ -2,5 +2,10 @@ Launching VM...
Setting IOThreads...
{u'return': {}}
{u'return': {}}
Enabling migration QMP events...
{u'return': {}}
Starting migration...
{u'return': {}}
{u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'status': u'setup'}, u'event': u'MIGRATION'}
{u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'status': u'active'}, u'event': u'MIGRATION'}
{u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'status': u'completed'}, u'event': u'MIGRATION'}