On Sat, 5 Nov 2022 15:44:57 -0700
Anthony DeRossi <ajderossi@xxxxxxxxx> 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@xxxxxxxxx>
> ---
> drivers/vfio/vfio_main.c | 11 +++++++++++
> include/linux/vfio.h | 1 +
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 9a4af880e941..ab34faabcebb 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -125,6 +125,17 @@ static void vfio_release_device_set(struct vfio_device *device)
> xa_unlock(&vfio_device_set_xa);
> }
>
> +unsigned int vfio_device_set_open_count(struct vfio_device_set *dev_set)
> +{
> + struct vfio_device *cur;
> + unsigned int open_count = 0;
This can only be called while holding the dev_set->lock, so we should
have an assert here:
lockdep_assert_held(&dev_set->lock);
The series looks ok to me otherwise, hopefully we'll get some
additional reviews. Thanks,
Alex
> +
> + list_for_each_entry(cur, &dev_set->device_list, dev_set_list)
> + open_count += cur->open_count;
> + return open_count;
> +}
> +EXPORT_SYMBOL_GPL(vfio_device_set_open_count);
> +
> /*
> * Group objects - create, release, get, put, search
> */
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index e7cebeb875dd..fdd393f70b19 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -189,6 +189,7 @@ int vfio_register_emulated_iommu_dev(struct vfio_device *device);
> void vfio_unregister_group_dev(struct vfio_device *device);
>
> int vfio_assign_device_set(struct vfio_device *device, void *set_id);
> +unsigned int vfio_device_set_open_count(struct vfio_device_set *dev_set);
>
> int vfio_mig_get_next_state(struct vfio_device *device,
> enum vfio_device_mig_state cur_fsm,
