> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Wednesday, March 24, 2021 1:55 AM
>
> struct mdev_type holds a pointer to the kref'd object struct mdev_parent,
> but doesn't hold the kref. The lifetime of the parent becomes implicit
> because parent_remove_sysfs_files() is supposed to remove all the access
> before the parent can be freed, but this is very hard to reason about.
>
> Make it obviously correct by adding the missing get.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> ---
> drivers/vfio/mdev/mdev_sysfs.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/vfio/mdev/mdev_sysfs.c
> b/drivers/vfio/mdev/mdev_sysfs.c
> index 5219cdd6dbbc49..d43775bd0ba340 100644
> --- a/drivers/vfio/mdev/mdev_sysfs.c
> +++ b/drivers/vfio/mdev/mdev_sysfs.c
> @@ -81,6 +81,8 @@ 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() */
> + mdev_put_parent(type->parent);
> kfree(type);
> }
>
> @@ -106,6 +108,8 @@ static struct mdev_type
> *add_mdev_supported_type(struct mdev_parent *parent,
>
> type->kobj.kset = parent->mdev_types_kset;
> type->parent = parent;
> + /* Pairs with the put in mdev_type_release() */
> + mdev_get_parent(parent);
>
> ret = kobject_init_and_add(&type->kobj, &mdev_type_ktype, NULL,
> "%s-%s", dev_driver_string(parent->dev),
> --
> 2.31.0
