migration: pre_save return int

Modify the pre_save method on VMStateDescription to return an int
rather than void so that it potentially can fail.

Changed zillions of devices to make them return 0; the only
case I've made it return non-0 is hw/intc/s390_flic_kvm.c that already
had an error_report/return case.

Note: If you add an error exit in your pre_save you must emit
an error_report to say why.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170925112917.21340-2-dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index ff1bb1534c..62d69aa30b 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -62,13 +62,15 @@ typedef struct VirtioCcwDeviceTmp {
     uint16_t config_vector;
 } VirtioCcwDeviceTmp;
 
-static void virtio_ccw_dev_tmp_pre_save(void *opaque)
+static int virtio_ccw_dev_tmp_pre_save(void *opaque)
 {
     VirtioCcwDeviceTmp *tmp = opaque;
     VirtioCcwDevice *dev = tmp->parent;
     VirtIODevice *vdev = virtio_bus_get_device(&dev->bus);
 
     tmp->config_vector = vdev->config_vector;
+
+    return 0;
 }
 
 static int virtio_ccw_dev_tmp_post_load(void *opaque, int version_id)