qapi: modify visitor code generation for list iteration

Modify logic such that we never assign values to the list head argument
to progress through the list on subsequent iterations, instead rely only
on having our return value passed back in as an argument on the next
call. Also update QMP I/O visitors and test cases accordingly, and add a
missing test case for QmpOutputVisitor.

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 252230ef25..62de83d0f0 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -79,11 +79,11 @@ def generate_visit_list(name, members):
 
 void visit_type_%(name)sList(Visitor *m, %(name)sList ** obj, const char *name, Error **errp)
 {
-    GenericList *i;
+    GenericList *i, **head = (GenericList **)obj;
 
     visit_start_list(m, name, errp);
 
-    for (i = visit_next_list(m, (GenericList **)obj, errp); i; i = visit_next_list(m, &i, errp)) {
+    for (*head = i = visit_next_list(m, head, errp); i; i = visit_next_list(m, &i, errp)) {
         %(name)sList *native_i = (%(name)sList *)i;
         visit_type_%(name)s(m, &native_i->value, NULL, errp);
     }