Re: [Qemu-devel] question on virtio ccw

[Cornelia Huck <cohuck@redhat.com>]

On Thu, 7 Dec 2017 19:18:44 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> I see this in ccw in qemu:
> 
>             if (virtio_set_status(vdev, status) == 0) {
>                 if (vdev->status == 0) {
>                     virtio_ccw_reset_virtio(dev, vdev);
>                 }
>                 if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
>                     virtio_ccw_start_ioeventfd(dev);
>                 }
>                 sch->curr_status.scsw.count = ccw.count - sizeof(status);
>                 ret = 0;
>             } else {
>                 /* Trigger a command reject. */
>                 ret = -ENOSYS;
>             }
> 
> virtio_set_status on success sets vdev->status to status.
> Why check vdev->status in one place and status in another?
> 

Probably for symmetry with the check whether to stop ioeventfd right
above. But it does not really matter one way or the other.