[Qemu-devel] [PATCH v9 18/37] qapi: Drop unused error argument for list and implicit struct

[Eric Blake]

No backend was setting an error when ending the visit of a list
or implicit struct.  Make the callers a bit easier to follow by
making this a part of the contract, and removing the errp
argument - callers can then unconditionally end an object as
part of cleanup without having to think about whether a second
error is dominated by a first, because there is no second error.

The only addition of &error_abort in this patch, in the function
qmp_input_end_list(), will never trigger unless a programming
bug creates a push(struct)/pop(list) or push(list)/pop(struct)
mismatch.

A later patch will then tackle the larger task of splitting
visit_end_struct(), which can indeed set an error (and that
cleanup will also have the side-effect of removing the use of
error_abort added here).

Signed-off-by: Eric Blake <address@hidden>
Reviewed-by: Marc-André Lureau <address@hidden>

---
v9: enhance commit message
v8: no change
v7: place earlier in series, rebase to earlier changes
v6: new patch, split from RFC on v5 7/46
---
 hw/ppc/spapr_drc.c           |  6 +-----
 include/qapi/visitor-impl.h  |  6 ++++--
 include/qapi/visitor.h       |  5 +++--
 qapi/opts-visitor.c          |  2 +-
 qapi/qapi-dealloc-visitor.c  |  4 ++--
 qapi/qapi-visit-core.c       |  8 ++++----
 qapi/qmp-input-visitor.c     |  9 ++-------
 qapi/qmp-output-visitor.c    |  2 +-
 qapi/string-input-visitor.c  |  2 +-
 qapi/string-output-visitor.c |  2 +-
 scripts/qapi-visit.py        | 10 +++-------
 11 files changed, 23 insertions(+), 33 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 78d71e2..ffc2cd9 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -314,11 +314,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const 
char *name,
                     return;
                 }
             }
-            visit_end_list(v, &err);
-            if (err) {
-                error_propagate(errp, err);
-                return;
-            }
+            visit_end_list(v);
             break;
         }
         default:
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 6abfda7..7f512cf 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -24,11 +24,13 @@ struct Visitor

     void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
                                   Error **errp);
-    void (*end_implicit_struct)(Visitor *v, Error **errp);
+    /* May be NULL */
+    void (*end_implicit_struct)(Visitor *v);

     void (*start_list)(Visitor *v, const char *name, Error **errp);
     GenericList *(*next_list)(Visitor *v, GenericList **list, Error **errp);
-    void (*end_list)(Visitor *v, Error **errp);
+    /* Must be set */
+    void (*end_list)(Visitor *v);

     void (*type_enum)(Visitor *v, const char *name, int *obj,
                       const char *const strings[], Error **errp);
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 4abc180..10390d2 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -32,10 +32,11 @@ void visit_start_struct(Visitor *v, const char *name, void 
**obj,
 void visit_end_struct(Visitor *v, Error **errp);
 void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp);
-void visit_end_implicit_struct(Visitor *v, Error **errp);
+void visit_end_implicit_struct(Visitor *v);
+
 void visit_start_list(Visitor *v, const char *name, Error **errp);
 GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp);
-void visit_end_list(Visitor *v, Error **errp);
+void visit_end_list(Visitor *v);

 /**
  * Check if an optional member @name of an object needs visiting.
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index 6d4a91e..62ffdd4 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -269,7 +269,7 @@ opts_next_list(Visitor *v, GenericList **list, Error **errp)


 static void
-opts_end_list(Visitor *v, Error **errp)
+opts_end_list(Visitor *v)
 {
     OptsVisitor *ov = to_ov(v);

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 49e7cf0..560feb3 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -83,7 +83,7 @@ static void qapi_dealloc_start_implicit_struct(Visitor *v,
     qapi_dealloc_push(qov, obj);
 }

-static void qapi_dealloc_end_implicit_struct(Visitor *v, Error **errp)
+static void qapi_dealloc_end_implicit_struct(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void **obj = qapi_dealloc_pop(qov);
@@ -119,7 +119,7 @@ static GenericList *qapi_dealloc_next_list(Visitor *v, 
GenericList **listp,
     return NULL;
 }

-static void qapi_dealloc_end_list(Visitor *v, Error **errp)
+static void qapi_dealloc_end_list(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void *obj = qapi_dealloc_pop(qov);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index b0452cf..2d3743b 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -37,10 +37,10 @@ void visit_start_implicit_struct(Visitor *v, void **obj, 
size_t size,
     }
 }

-void visit_end_implicit_struct(Visitor *v, Error **errp)
+void visit_end_implicit_struct(Visitor *v)
 {
     if (v->end_implicit_struct) {
-        v->end_implicit_struct(v, errp);
+        v->end_implicit_struct(v);
     }
 }

@@ -54,9 +54,9 @@ GenericList *visit_next_list(Visitor *v, GenericList **list, 
Error **errp)
     return v->next_list(v, list, errp);
 }

-void visit_end_list(Visitor *v, Error **errp)
+void visit_end_list(Visitor *v)
 {
-    v->end_list(v, errp);
+    v->end_list(v);
 }

 bool visit_start_union(Visitor *v, bool data_present, Error **errp)
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index bf25249..597652c 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -153,10 +153,6 @@ static void qmp_input_start_implicit_struct(Visitor *v, 
void **obj,
     }
 }

-static void qmp_input_end_implicit_struct(Visitor *v, Error **errp)
-{
-}
-
 static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -201,11 +197,11 @@ static GenericList *qmp_input_next_list(Visitor *v, 
GenericList **list,
     return entry;
 }

-static void qmp_input_end_list(Visitor *v, Error **errp)
+static void qmp_input_end_list(Visitor *v)
 {
     QmpInputVisitor *qiv = to_qiv(v);

-    qmp_input_pop(qiv, errp);
+    qmp_input_pop(qiv, &error_abort);
 }

 static void qmp_input_get_next_type(Visitor *v, const char *name, QType *type,
@@ -352,7 +348,6 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.start_struct = qmp_input_start_struct;
     v->visitor.end_struct = qmp_input_end_struct;
     v->visitor.start_implicit_struct = qmp_input_start_implicit_struct;
-    v->visitor.end_implicit_struct = qmp_input_end_implicit_struct;
     v->visitor.start_list = qmp_input_start_list;
     v->visitor.next_list = qmp_input_next_list;
     v->visitor.end_list = qmp_input_end_list;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index db5e618..d367148 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -151,7 +151,7 @@ static GenericList *qmp_output_next_list(Visitor *v, 
GenericList **listp,
     return list ? list->next : NULL;
 }

-static void qmp_output_end_list(Visitor *v, Error **errp)
+static void qmp_output_end_list(Visitor *v)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_pop(qov);
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 5347b61..610c233 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -178,7 +178,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 }

 static void
-end_list(Visitor *v, Error **errp)
+end_list(Visitor *v)
 {
     StringInputVisitor *siv = to_siv(v);
     siv->head = true;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 74de6b6..fd917a4 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -303,7 +303,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 }

 static void
-end_list(Visitor *v, Error **errp)
+end_list(Visitor *v)
 {
     StringOutputVisitor *sov = to_sov(v);

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 8a741b6..573bb81 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -62,7 +62,7 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, 
%(c_type)s **obj, Error *
     visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err);
     if (!err) {
         visit_type_%(c_type)s_fields(v, obj, errp);
-        visit_end_implicit_struct(v, &err);
+        visit_end_implicit_struct(v);
     }
     error_propagate(errp, err);
 }
@@ -167,9 +167,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, 
%(c_name)s **obj, Error
         visit_type_%(c_elt_type)s(v, NULL, &native_i->value, &err);
     }

-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_list(v, &err);
+    visit_end_list(v);
 out:
     error_propagate(errp, err);
 }
@@ -230,9 +228,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, 
%(c_name)s **obj, Error
                    "%(name)s");
     }
 out_obj:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_implicit_struct(v, &err);
+    visit_end_implicit_struct(v);
 out:
     error_propagate(errp, err);
 }
-- 
2.5.0