qdev: Make netdev properties work as list elements

The 'name' parameter of QOM setters is primarily used to specify the name
of the currently parsed input element in the visitor interface. For
top-level qdev properties, this is always set and matches 'prop->name'.

However, for list elements it is NULL, because each element of a list
doesn't have a separate name. Passing a non-NULL value runs into
assertion failures in the visitor code.

Therefore, using 'name' in error messages is not right for property
types that are used in lists, because "(null)" (or even a segfault)
isn't very helpful to identify what QEMU is complaining about.

Change netdev properties to use 'prop->name' instead, which will contain
the name of the array property after switching array properties to lists
in the external interface. (This is still not perfect, as it doesn't
identify which element in the list caused the error, but strictly better
than before.)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231109174240.72376-11-kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/core/qdev-properties-system.c

@@ -450,7 +450,7 @@ static void set_netdev(Object *obj, Visitor *v, const char *name,
     peers_ptr->queues = queues;
 
 out:
-    error_set_from_qdev_prop_error(errp, err, obj, name, str);
+    error_set_from_qdev_prop_error(errp, err, obj, prop->name, str);
     g_free(str);
 }