Replace raw object_ref/unref calls with iothread_get/put_aio_context.

Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 hw/virtio/virtio-balloon.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 38bf1e84a1..4eeae48b50 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -895,14 +895,18 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
     s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
 
     if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
+        char *path = object_get_canonical_path(OBJECT(s));
+
         s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE,
                                            virtio_balloon_handle_free_page_vq);
         precopy_add_notifier(&s->free_page_hint_notify);
 
-        object_ref(OBJECT(s->iothread));
-        s->free_page_bh = aio_bh_new_guarded(iothread_get_aio_context(s->iothread),
-                                             virtio_ballloon_get_free_page_hints, s,
-                                             &dev->mem_reentrancy_guard);
+        s->free_page_bh = aio_bh_new_guarded(
+                              iothread_get_aio_context(s->iothread, path),
+                              virtio_ballloon_get_free_page_hints, s,
+                              &dev->mem_reentrancy_guard);
+
+        g_free(path);
     }
 
     if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_REPORTING)) {
@@ -922,10 +926,13 @@ static void virtio_balloon_device_unrealize(DeviceState *dev)
 
     qemu_unregister_resettable(OBJECT(dev));
     if (s->free_page_bh) {
+        char *path = object_get_canonical_path(OBJECT(s));
+
         qemu_bh_delete(s->free_page_bh);
-        object_unref(OBJECT(s->iothread));
         virtio_balloon_free_page_stop(s);
+        iothread_put_aio_context(s->iothread, path);
         precopy_remove_notifier(&s->free_page_hint_notify);
+        g_free(path);
     }
     balloon_stats_destroy_timer(s);
     qemu_remove_balloon_handler(s);
-- 
2.49.0