fix qmp-cont vs migration-finish race-crash

[Qemu-devel] [PATCH 0/2] fix qmp-cont vs migration-finish race-crash

Posted by Vladimir Sementsov-Ogievskiy 6 years, 9 months ago

Hi.

It's a simple fix for problems reported in "Aborts in iotest 169"
by Max:
https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg05907.html

In thread Kevin described that a problem itself is bigger and needs
more effort:
https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg06136.html

So, we may continue discussion in "Aborts in iotest 169", and in
parallel apply these patches at least as a temporary fix.

The problem of this fix is that we finally have a bit weird interface:

User gets event MIGRATION_COMPLETED, and after it he can get error
message "Migration is not finalized yet". 

But it is better than crash, anyway.

Vladimir Sementsov-Ogievskiy (2):
  qmp: forbid qmp_cont in RUN_STATE_FINISH_MIGRATE
  iotest: fix 169: do not run qmp_cont in RUN_STATE_FINISH_MIGRATE

 qmp.c                  | 3 +++
 tests/qemu-iotests/169 | 7 ++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

-- 
2.18.0

Re: [Qemu-devel] [PATCH 0/2] fix qmp-cont vs migration-finish race-crash

Posted by Thomas Huth 6 years, 6 months ago

On 24/01/2019 13.25, Vladimir Sementsov-Ogievskiy wrote:
> Hi.
> 
> It's a simple fix for problems reported in "Aborts in iotest 169"
> by Max:
> https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg05907.html
> 
> In thread Kevin described that a problem itself is bigger and needs
> more effort:
> https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg06136.html
> 
> So, we may continue discussion in "Aborts in iotest 169", and in
> parallel apply these patches at least as a temporary fix.
> 
> The problem of this fix is that we finally have a bit weird interface:
> 
> User gets event MIGRATION_COMPLETED, and after it he can get error
> message "Migration is not finalized yet". 
> 
> But it is better than crash, anyway.
> 
> Vladimir Sementsov-Ogievskiy (2):
>   qmp: forbid qmp_cont in RUN_STATE_FINISH_MIGRATE
>   iotest: fix 169: do not run qmp_cont in RUN_STATE_FINISH_MIGRATE

What happened to these two patches? As far as I can see, they've never
got applied? Has another fix for 169 included instead?

 Thomas

Re: [Qemu-devel] [PATCH 0/2] fix qmp-cont vs migration-finish race-crash

Posted by Dr. David Alan Gilbert 6 years, 5 months ago

* Thomas Huth (thuth@redhat.com) wrote:
> On 24/01/2019 13.25, Vladimir Sementsov-Ogievskiy wrote:
> > Hi.
> > 
> > It's a simple fix for problems reported in "Aborts in iotest 169"
> > by Max:
> > https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg05907.html
> > 
> > In thread Kevin described that a problem itself is bigger and needs
> > more effort:
> > https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg06136.html
> > 
> > So, we may continue discussion in "Aborts in iotest 169", and in
> > parallel apply these patches at least as a temporary fix.
> > 
> > The problem of this fix is that we finally have a bit weird interface:
> > 
> > User gets event MIGRATION_COMPLETED, and after it he can get error
> > message "Migration is not finalized yet". 
> > 
> > But it is better than crash, anyway.
> > 
> > Vladimir Sementsov-Ogievskiy (2):
> >   qmp: forbid qmp_cont in RUN_STATE_FINISH_MIGRATE
> >   iotest: fix 169: do not run qmp_cont in RUN_STATE_FINISH_MIGRATE
> 
> What happened to these two patches? As far as I can see, they've never
> got applied? Has another fix for 169 included instead?

Hmm not sure; they've slipped between the maintainers if not.
1/2 is a qmp.c so while it fixes a migration corner case it's probably
armbru that should take it.

Dave

>  Thomas
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] [PATCH 0/2] fix qmp-cont vs migration-finish race-crash

Posted by Kevin Wolf 6 years, 5 months ago

Am 24.01.2019 um 13:25 hat Vladimir Sementsov-Ogievskiy geschrieben:
> Hi.
> 
> It's a simple fix for problems reported in "Aborts in iotest 169"
> by Max:
> https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg05907.html
> 
> In thread Kevin described that a problem itself is bigger and needs
> more effort:
> https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg06136.html
> 
> So, we may continue discussion in "Aborts in iotest 169", and in
> parallel apply these patches at least as a temporary fix.
> 
> The problem of this fix is that we finally have a bit weird interface:
> 
> User gets event MIGRATION_COMPLETED, and after it he can get error
> message "Migration is not finalized yet". 
> 
> But it is better than crash, anyway.

Thanks, applied to the block branch.

Kevin