virtio: allow finalize_features to fail

This will make it easy for transports to validate features and return
failure.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index c792b5f..789275f 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -752,7 +752,7 @@
 	return rc;
 }
 
-static void virtio_ccw_finalize_features(struct virtio_device *vdev)
+static int virtio_ccw_finalize_features(struct virtio_device *vdev)
 {
 	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
 	struct virtio_feature_desc *features;
@@ -760,7 +760,7 @@
 
 	ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
 	if (!ccw)
-		return;
+		return 0;
 
 	features = kzalloc(sizeof(*features), GFP_DMA | GFP_KERNEL);
 	if (!features)
@@ -793,6 +793,8 @@
 out_free:
 	kfree(features);
 	kfree(ccw);
+
+	return 0;
 }
 
 static void virtio_ccw_get_config(struct virtio_device *vdev,