Re: [Qemu-devel] [PATCH 2/3] Migration/colo.c: Fix COLO failover status error

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Zhang, Chen (chen.zhang@intel.com) wrote:
> 
> -----Original Message-----
> From: Dr. David Alan Gilbert [mailto:dgilbert@redhat.com] 
> Sent: Tuesday, February 26, 2019 6:55 PM
> To: Zhang, Chen <chen.zhang@intel.com>
> Cc: Li Zhijian <lizhijian@cn.fujitsu.com>; Zhang Chen <zhangckid@gmail.com>; Juan Quintela <quintela@redhat.com>; zhanghailiang <zhang.zhanghailiang@huawei.com>; qemu-dev <qemu-devel@nongnu.org>
> Subject: Re: [PATCH 2/3] Migration/colo.c: Fix COLO failover status error
> 
> * Zhang Chen (chen.zhang@intel.com) wrote:
> > From: Zhang Chen <chen.zhang@intel.com>
> > 
> > When finished COLO failover, the status is FAILOVER_STATUS_COMPLETED.
> > The origin codes misunderstand the FAILOVER_STATUS_REQUIRE.
> > 
> > Signed-off-by: Zhang Chen <chen.zhang@intel.com>
> 
> > Why do these 'case's have to only deal with COMPLETED - what stops the REQUIRE/ACTIVE states appearing when these routines check the status; even if those states only happen for a short amount of time?
> 
> Yes, other status just marked the failover processing. We can see colo_failover_bh(), the REQUIRE/ACTIVE only exist for a very short time.

But those other states do exist - so don't these case statements have to
do something with them?

Dave

> 
> Thanks
> Zhang Chen
> 
> Dave
> 
> > ---
> >  migration/colo.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/migration/colo.c b/migration/colo.c index 
> > a916dc178c..a13acac192 100644
> > --- a/migration/colo.c
> > +++ b/migration/colo.c
> > @@ -121,6 +121,7 @@ static void secondary_vm_do_failover(void)
> >      }
> >      /* Notify COLO incoming thread that failover work is finished */
> >      qemu_sem_post(&mis->colo_incoming_sem);
> > +
> >      /* For Secondary VM, jump to incoming co */
> >      if (mis->migration_incoming_co) {
> >          qemu_coroutine_enter(mis->migration_incoming_co);
> > @@ -262,7 +263,7 @@ COLOStatus *qmp_query_colo_status(Error **errp)
> >      case FAILOVER_STATUS_NONE:
> >          s->reason = COLO_EXIT_REASON_NONE;
> >          break;
> > -    case FAILOVER_STATUS_REQUIRE:
> > +    case FAILOVER_STATUS_COMPLETED:
> >          s->reason = COLO_EXIT_REASON_REQUEST;
> >          break;
> >      default:
> > @@ -582,7 +583,7 @@ out:
> >          qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
> >                                    COLO_EXIT_REASON_ERROR);
> >          break;
> > -    case FAILOVER_STATUS_REQUIRE:
> > +    case FAILOVER_STATUS_COMPLETED:
> >          qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
> >                                    COLO_EXIT_REASON_REQUEST);
> >          break;
> > @@ -854,7 +855,7 @@ out:
> >          qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
> >                                    COLO_EXIT_REASON_ERROR);
> >          break;
> > -    case FAILOVER_STATUS_REQUIRE:
> > +    case FAILOVER_STATUS_COMPLETED:
> >          qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
> >                                    COLO_EXIT_REASON_REQUEST);
> >          break;
> > --
> > 2.17.GIT
> > 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK