RE: [PATCH 6/6] migration/colo.c: Move colo_notify_compares_event to the right place

[Zhanghailiang <zhang.zhanghailiang@huawei.com>]

Reviewed-by: zhanghailiang <zhang.zhanghailiang@huawei.com>

> -----Original Message-----
> From: Lukas Straub [mailto:lukasstraub2@web.de]
> Sent: Monday, May 11, 2020 7:11 PM
> To: qemu-devel <qemu-devel@nongnu.org>
> Cc: Zhanghailiang <zhang.zhanghailiang@huawei.com>; Juan Quintela
> <quintela@redhat.com>; Dr. David Alan Gilbert <dgilbert@redhat.com>
> Subject: [PATCH 6/6] migration/colo.c: Move colo_notify_compares_event
> to the right place
> 
> If the secondary has to failover during checkpointing, it still is in the old state
> (i.e. different state than primary). Thus we can't expose the primary state
> until after the checkpoint is sent.
> 
> This fixes sporadic connection reset of client connections during failover.
> 
> Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> ---
>  migration/colo.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/migration/colo.c b/migration/colo.c index
> a69782efc5..a3fc21e86e 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -430,12 +430,6 @@ static int
> colo_do_checkpoint_transaction(MigrationState *s,
>          goto out;
>      }
> 
> -    qemu_event_reset(&s->colo_checkpoint_event);
> -    colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT,
> &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -
>      /* Disable block migration */
>      migrate_set_block_enabled(false, &local_err);
>      qemu_mutex_lock_iothread();
> @@ -494,6 +488,12 @@ static int
> colo_do_checkpoint_transaction(MigrationState *s,
>          goto out;
>      }
> 
> +    qemu_event_reset(&s->colo_checkpoint_event);
> +    colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT,
> &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +
>      colo_receive_check_message(s->rp_state.from_dst_file,
>                         COLO_MESSAGE_VMSTATE_LOADED, &local_err);
>      if (local_err) {
> --
> 2.20.1