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, 1 insertions, 1 deletions

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 85e43da..da46b1a 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -179,7 +179,7 @@ struct VMStateDescription {
     LoadStateHandler *load_state_old;
     int (*pre_load)(void *opaque);
     int (*post_load)(void *opaque, int version_id);
-    void (*pre_save)(void *opaque);
+    int (*pre_save)(void *opaque);
     bool (*needed)(void *opaque);
     VMStateField *fields;
     const VMStateDescription **subsections;