Re: [Qemu-devel] [PATCH] object_del: Prevent removing an in-use memory backend object

[Igor Mammedov]

On Fri, 20 Mar 2015 12:14:58 +0800
Lin Ma <address@hidden> wrote:

> showing a memory device whose memdev is removed leads an assert:
> 
> (qemu) object_add memory-backend-ram,id=ram0,size=128M
> (qemu) device_add pc-dimm,id=d0,memdev=ram0
> (qemu) object_del ram0
> (qemu) info memory-devices
> **
> ERROR:qom/object.c:1274:object_get_canonical_path_component:\
>                             assertion failed: (obj->parent != NULL)
> Aborted
> 
> The patch prevents removing an in-use mem backend and outputs an error msg.
> 
> Signed-off-by: Lin Ma <address@hidden>
> ---
>  qmp.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/qmp.c b/qmp.c
> index c479e77..0086e2d 100644
> --- a/qmp.c
> +++ b/qmp.c
> @@ -704,6 +704,7 @@ void qmp_object_del(const char *id, Error **errp)
>  {
>      Object *container;
>      Object *obj;
> +    const char *typename;
>  
>      container = container_get(object_get_root(), "/objects");
>      obj = object_resolve_path_component(container, id);
> @@ -711,6 +712,19 @@ void qmp_object_del(const char *id, Error **errp)
>          error_setg(errp, "object id not found");
>          return;
>      }
> +
> +    typename = object_class_get_name(object_class_get_parent(\
> +                                        object_get_class(OBJECT(obj))));
> +    if (strcmp(typename, TYPE_MEMORY_BACKEND) == 0 ) {
> +        MemoryRegion *mr;
> +        mr = host_memory_backend_get_memory(MEMORY_BACKEND(obj), errp);
> +        if (memory_region_is_mapped(mr)) {
> +            char *path = object_get_canonical_path_component(obj);
> +            error_setg(errp, "memdev %s is in used.", path);
> +            g_free(path);
> +            return;
> +        }
> +    }
How about making it more generic?
i.e
  if (!obj_class->can_be_deleted(obj))
     error out

>      object_unparent(obj);
>  }
>