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

[Lin Ma]

Igor,

It seems my smtp server has some issues, The email including my reply doesn't hit the list.
I paste my reply here and send it again:

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 the callback impl in hostmem-ram.c and hostmem-file.c

thanks,
Lin

>>> Igor Mammedov <address@hidden> 2015-3-20 下午 18:18 >>>
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);
> }
>