Re: [PATCH 15/15] vfio/mdev: remove an extra parent kobject reference

Kirti Wankhede
2022-07-06T13:49:14Z

On 7/6/2022 1:12 PM, Christoph Hellwig wrote:
> The mdev_type already holds a reference to the parent through
> mdev_types_kset, so drop the extra reference.
>
> Suggested-by: Kirti Wankhede <kwankhede@nvidia.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/vfio/mdev/mdev_sysfs.c | 9 +--------
> 1 file changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
> index c5cd035d591d0..e2087cac1c859 100644
> --- a/drivers/vfio/mdev/mdev_sysfs.c
> +++ b/drivers/vfio/mdev/mdev_sysfs.c
> @@ -153,8 +153,6 @@ static void mdev_type_release(struct kobject *kobj)
> struct mdev_type *type = to_mdev_type(kobj);
>
> pr_debug("Releasing group %s\n", kobj->name);
> - /* Pairs with the get in add_mdev_supported_type() */
> - put_device(type->parent->dev);
> kfree(type);
> }
>
> @@ -170,16 +168,12 @@ static int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type)
>
> type->kobj.kset = parent->mdev_types_kset;
> type->parent = parent;
> - /* Pairs with the put in mdev_type_release() */
> - get_device(parent->dev);
>
> ret = kobject_init_and_add(&type->kobj, &mdev_type_ktype, NULL,
> "%s-%s", dev_driver_string(parent->dev),
> type->sysfs_name);
> - if (ret) {
> - kobject_put(&type->kobj);

This kobject_put is required here in error case, see description above
kobject_init_and_add().

> + if (ret)
> return ret;
> - }
>
> type->devices_kobj = kobject_create_and_add("devices", &type->kobj);
> if (!type->devices_kobj) {
> @@ -191,7 +185,6 @@ static int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type)
>
> attr_devices_failed:
> kobject_del(&type->kobj);
> - kobject_put(&type->kobj);

Same as above.

Thanks,
Kirti