migration: Route errors up through vmstate_save

Route the errors from vsmtate_save_state back up through
vmstate_save and out to the normal device state path.
That's the normal error path done.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170925112917.21340-6-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>

migration/savevm.c

@@ -768,14 +768,14 @@ static void vmstate_save_old_style(QEMUFile *f, SaveStateEntry *se, QJSON *vmdes
     }
 }
 
-static void vmstate_save(QEMUFile *f, SaveStateEntry *se, QJSON *vmdesc)
+static int vmstate_save(QEMUFile *f, SaveStateEntry *se, QJSON *vmdesc)
 {
     trace_vmstate_save(se->idstr, se->vmsd ? se->vmsd->name : "(old)");
     if (!se->vmsd) {
         vmstate_save_old_style(f, se, vmdesc);
-        return;
+        return 0;
     }
-    vmstate_save_state(f, se->vmsd, se->opaque, vmdesc);
+    return vmstate_save_state(f, se->vmsd, se->opaque, vmdesc);
 }
 
 /*
@@ -1171,7 +1171,11 @@ int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
         json_prop_int(vmdesc, "instance_id", se->instance_id);
 
         save_section_header(f, se, QEMU_VM_SECTION_FULL);
-        vmstate_save(f, se, vmdesc);
+        ret = vmstate_save(f, se, vmdesc);
+        if (ret) {
+            qemu_file_set_error(f, ret);
+            return ret;
+        }
         trace_savevm_section_end(se->idstr, se->section_id, 0);
         save_section_footer(f, se);
 
@@ -1313,6 +1317,8 @@ static int qemu_save_device_state(QEMUFile *f)
     cpu_synchronize_all_states();
 
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
+        int ret;
+
         if (se->is_ram) {
             continue;
         }
@@ -1325,7 +1331,10 @@ static int qemu_save_device_state(QEMUFile *f)
 
         save_section_header(f, se, QEMU_VM_SECTION_FULL);
 
-        vmstate_save(f, se, NULL);
+        ret = vmstate_save(f, se, NULL);
+        if (ret) {
+            return ret;
+        }
 
         save_section_footer(f, se);
     }