Re: [Qemu-devel] [PATCH] Migration: Generate the completed event only when we complete

[Juan Quintela <quintela@redhat.com>]

"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> The current migration-completed event is generated a bit too early,
> which means that an eager libvirt that's ready to go as soon
> as it sees the event ends up racing with the actual end of migration.
>
> This corresponds to RH bug:
> https://bugzilla.redhat.com/show_bug.cgi?id=1271145
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>


Applied.


> ---
>  migration/migration.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index b7de9b7..3d40f24 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -294,12 +294,12 @@ static void process_incoming_migration_co(void *opaque)
>          migrate_decompress_threads_join();
>          exit(EXIT_FAILURE);
>      }
> -    migrate_generate_event(MIGRATION_STATUS_COMPLETED);
>      qemu_announce_self();
>  
>      /* Make sure all file formats flush their mutable metadata */
>      bdrv_invalidate_cache_all(&local_err);
>      if (local_err) {
> +        migrate_generate_event(MIGRATION_STATUS_FAILED);
>          error_report_err(local_err);
>          migrate_decompress_threads_join();
>          exit(EXIT_FAILURE);
> @@ -320,6 +320,12 @@ static void process_incoming_migration_co(void *opaque)
>          runstate_set(global_state_get_runstate());
>      }
>      migrate_decompress_threads_join();
> +    /*
> +     * This must happen after any state changes since as soon as an external
> +     * observer sees this event they might start to prod at the VM assuming
> +     * it's ready to use.
> +     */
> +    migrate_generate_event(MIGRATION_STATUS_COMPLETED);
>  }
>  
>  void process_incoming_migration(QEMUFile *f)