[Qemu-devel] [PATCH v3 1/2] qom: Add can_be_deleted callback to UserCreatableClass

[Lin Ma <lma@suse.com>]

If backends implement the can_be_deleted and it returns false,
Then the qmp_object_del won't delete the given backends.

Signed-off-by: Lin Ma <lma@suse.com>
---
 include/qom/object_interfaces.h |  3 +++
 qmp.c                           | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/include/qom/object_interfaces.h b/include/qom/object_interfaces.h
index b792283..19b66f1 100644
--- a/include/qom/object_interfaces.h
+++ b/include/qom/object_interfaces.h
@@ -25,6 +25,8 @@ typedef struct UserCreatable {
  * UserCreatableClass:
  * @parent_class: the base class
  * @complete: callback to be called after @obj's properties are set.
+ * @can_be_deleted: callback to be called before an object is removed
+ * to check if @obj can be removed safely.
  *
  * Interface is designed to work with -object/object-add/object_add
  * commands.
@@ -47,6 +49,7 @@ typedef struct UserCreatableClass {
 
     /* <public> */
     void (*complete)(UserCreatable *uc, Error **errp);
+    bool (*can_be_deleted)(UserCreatable *uc, Error **errp);
 } UserCreatableClass;
 
 /**
diff --git a/qmp.c b/qmp.c
index c479e77..a9156d6 100644
--- a/qmp.c
+++ b/qmp.c
@@ -711,6 +711,19 @@ void qmp_object_del(const char *id, Error **errp)
         error_setg(errp, "object id not found");
         return;
     }
+
+    UserCreatableClass *ucc;
+    UserCreatable *uc =
+        (UserCreatable *)object_dynamic_cast(obj, TYPE_USER_CREATABLE);
+    ucc = USER_CREATABLE_GET_CLASS(uc);
+    if (ucc->can_be_deleted) {
+        if (!ucc->can_be_deleted(uc, errp)) {
+            char *path = object_get_canonical_path_component(obj);
+            error_setg(errp, "%s is in used, can not be deleted", path);
+            g_free(path);
+            return;
+        }
+    }
     object_unparent(obj);
 }
 
-- 
2.1.4