On Thu, 29 Oct 2020 19:29:35 -0400
Tony Krowiak <akrow...@linux.ibm.com> wrote:
> >> @@ -1177,7 +1166,10 @@ static int vfio_ap_mdev_reset_queues(struct
> >> mdev_device *mdev)
> >> */
> >> if (ret)
> >> rc = ret;
> >> - vfio_ap_irq_disable_apqn(AP_MKQID(apid, apqi));
> >> + q = vfio_ap_get_queue(matrix_mdev,
> >> + AP_MKQID(apid, apqi));
> >> + if (q)
> >> + vfio_ap_free_aqic_resources(q);
[..]
> >
> > Under what circumstances do we expect !q? If we don't, then we need to
> > complain one way or another.
>
> In the current code (i.e., prior to introducing the subsequent hot
> plug patches), an APQN can not be assigned to an mdev unless it
> references a queue device bound to the vfio_ap device driver; however,
> there is nothing preventing a queue device from getting unbound
> while the guest is running (one of the problems mostly resolved by this
> series). In that case, q would be NULL.
But if the queue does not belong to us any more it does not make sense
call vfio_ap_mdev_reset_queue() on it's APQN, or?
I think we should have
if(!q)
continue;
at the very beginning of the loop body, or we want to be sure that q is
not null.
