Re: [PATCH kernel v2 10/11] vfio: Check for unregistered notifiers when group is actually released

[Jike Song <jike.song@intel.com>]

On 12/18/2016 09:28 AM, Alexey Kardashevskiy wrote:
> This moves a check for unregistered notifiers from fops release
> callback to the place where the group will actually be released.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> 
> This is going to be used in the following patch in cleanup
> path. Since the next patch is RFC, this one might not be needed.

Hi Alexey,

I didn't find any use in the following patch 11/11, did you mean
something else?

BTW the warning in vfio_group_release seems too late, the user
should actually unregister everything by close()?

--
Thanks,
Jike

> ---
>  drivers/vfio/vfio.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 6b9a98508939..083b581e87c0 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -403,6 +403,8 @@ static void vfio_group_release(struct kref *kref)
>  	struct iommu_group *iommu_group = group->iommu_group;
>  
>  	WARN_ON(!list_empty(&group->device_list));
> +	/* Any user didn't unregister? */
> +	WARN_ON(group->notifier.head);
>  
>  	list_for_each_entry_safe(unbound, tmp,
>  				 &group->unbound_list, unbound_next) {
> @@ -1584,9 +1586,6 @@ static int vfio_group_fops_release(struct inode *inode, struct file *filep)
>  
>  	filep->private_data = NULL;
>  
> -	/* Any user didn't unregister? */
> -	WARN_ON(group->notifier.head);
> -
>  	vfio_group_try_dissolve_container(group);
>  
>  	atomic_dec(&group->opened);
>