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

[Lin Ma]

在 2015年03月20日 18:17, Igor Mammedov 写道:
> 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);
> >   }
> >   
That makes sense, I couldn't agree more.
I am going to drop this patch and separate it to 2 patches. One for 
adding generic can_be_deleted
callback, The other for adding impl in hostmem-ram.c and hostmem-file.c

thanks,
Lin