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

[Lin Ma <lma@novell.com>]

在 2015年03月20日 18:17, Igor Mammedov 写道:
> On Fri, 20 Mar 2015 12:14:58 +0800
> Lin Ma <lma@suse.com> 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 <lma@suse.com>
>> ---
>>   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