Re: [PATCH v5 2/3] vfio: Export the device set open count

[Jason Gunthorpe <jgg@ziepe.ca>]

On Sat, Nov 05, 2022 at 03:44:57PM -0700, Anthony DeRossi wrote:
> The open count of a device set is the sum of the open counts of all
> devices in the set. Drivers can use this value to determine whether
> shared resources are in use without tracking them manually or accessing
> the private open_count in vfio_device.
> 
> Signed-off-by: Anthony DeRossi <ajderossi@gmail.com>
> ---
>  drivers/vfio/vfio_main.c | 11 +++++++++++
>  include/linux/vfio.h     |  1 +
>  2 files changed, 12 insertions(+)

>  
> +unsigned int vfio_device_set_open_count(struct vfio_device_set *dev_set)
> +{
> +	struct vfio_device *cur;
> +	unsigned int open_count = 0;

I'd probably just make this a bool

'vfio_device_set_last_close()'

And roll in the < 1 logic too

Nothing will ever need to know the number of fds open across the set.

But this is fine as written

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason