[PATCH v4 1/2] migration/vmstate: Introduce vmstate_save_state_with_err

[Tejus GK]

Currently, a few code paths exist in the function vmstate_save_state_v,
which ultimately leads to a migration failure. However, an update in the
current MigrationState for the error description is never done.

vmstate.c somehow doesn't seem to allow the use of migrate_set_error due
to some dependencies for unit tests. Hence, this patch introduces a new
function vmstate_save_state_with_err, which will eventually propagate
the error message to savevm.c where a migrate_set_error call can be
eventually done.

Acked-by: Peter Xu <pet...@redhat.com>
Signed-off-by: Tejus GK <tejus...@nutanix.com>
---
 include/migration/vmstate.h |  4 +++-
 migration/savevm.c          |  2 +-
 migration/vmstate.c         | 12 +++++++++---
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index d1b8abe08d..2eb6002b3c 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -1194,9 +1194,11 @@ int vmstate_load_state(QEMUFile *f, const 
VMStateDescription *vmsd,
                        void *opaque, int version_id);
 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                        void *opaque, JSONWriter *vmdesc);
+int vmstate_save_state_with_err(QEMUFile *f, const VMStateDescription *vmsd,
+                       void *opaque, JSONWriter *vmdesc, Error **errp);
 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
                          void *opaque, JSONWriter *vmdesc,
-                         int version_id);
+                         int version_id, Error **errp);
 
 bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque);
 
diff --git a/migration/savevm.c b/migration/savevm.c
index a2cb8855e2..6c404ead1e 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1000,7 +1000,7 @@ static int vmstate_save(QEMUFile *f, SaveStateEntry *se, 
JSONWriter *vmdesc)
     if (!se->vmsd) {
         vmstate_save_old_style(f, se, vmdesc);
     } else {
-        ret = vmstate_save_state(f, se->vmsd, se->opaque, vmdesc);
+        ret = vmstate_save_state_with_err(f, se->vmsd, se->opaque, vmdesc, 
&local_err);
         if (ret) {
             return ret;
         }
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 31842c3afb..417a83215d 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -315,11 +315,17 @@ bool vmstate_save_needed(const VMStateDescription *vmsd, 
void *opaque)
 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                        void *opaque, JSONWriter *vmdesc_id)
 {
-    return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id);
+    return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, 
NULL);
+}
+
+int vmstate_save_state_with_err(QEMUFile *f, const VMStateDescription *vmsd,
+                       void *opaque, JSONWriter *vmdesc_id, Error **errp)
+{
+    return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, 
errp);
 }
 
 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
-                         void *opaque, JSONWriter *vmdesc, int version_id)
+                         void *opaque, JSONWriter *vmdesc, int version_id, 
Error **errp)
 {
     int ret = 0;
     const VMStateField *field = vmsd->fields;
@@ -377,7 +383,7 @@ int vmstate_save_state_v(QEMUFile *f, const 
VMStateDescription *vmsd,
                 } else if (field->flags & VMS_VSTRUCT) {
                     ret = vmstate_save_state_v(f, field->vmsd, curr_elem,
                                                vmdesc_loop,
-                                               field->struct_version_id);
+                                               field->struct_version_id, errp);
                 } else {
                     ret = field->info->put(f, curr_elem, size, field,
                                      vmdesc_loop);
-- 
2.22.3