Re: [PATCH v8 07/10] s390/vfio_ccw: cancel existing workqueues

[Matthew Rosato <mjrosato@linux.ibm.com>]

On 7/27/26 9:35 PM, Eric Farman wrote:
> The initialization of the io_work and crw_work workqueues begs the
> question of whether they should be un-initialized. Add the corresponding
> cleanup tags in _release_dev to ensure work isn't dispatched after
> the private struct is free'd.
> 
> Suggested-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Fixes: e5f84dbaea59 ("vfio: ccw: return I/O results asynchronously")
> Fixes: 3f02cb2fd9d2 ("vfio-ccw: Wire up the CRW irq and CRW region")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Farman <farman@linux.ibm.com>

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>

> ---
>  drivers/s390/cio/vfio_ccw_ops.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> index 032a1cdf4df7..bc8eb485d03f 100644
> --- a/drivers/s390/cio/vfio_ccw_ops.c
> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> @@ -131,6 +131,13 @@ static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev)
>  		container_of(vdev, struct vfio_ccw_private, vdev);
>  	struct vfio_ccw_crw *crw, *temp;
>  
> +	/*
> +	 * Ensure these work items are fully drained, so none can
> +	 * fire after being released.
> +	 */
> +	cancel_work_sync(&private->io_work);
> +	cancel_work_sync(&private->crw_work);
> +
>  	list_for_each_entry_safe(crw, temp, &private->crw, next) {
>  		list_del(&crw->next);
>  		kfree(crw);
> @@ -202,6 +209,14 @@ static void vfio_ccw_mdev_close_device(struct vfio_device *vdev)
>  		container_of(vdev, struct vfio_ccw_private, vdev);
>  
>  	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);
> +
> +	/*
> +	 * Ensure these work items are drained, in the event the
> +	 * device is re-opened instead of released
> +	 */
> +	cancel_work_sync(&private->io_work);
> +	cancel_work_sync(&private->crw_work);
> +
>  	vfio_ccw_unregister_dev_regions(private);
>  }
>