Re: [PATCH v4 3/7] s390: ap: associate a ap_vfio_queue and a matrix mdev

[Pierre Morel]

On 04/03/2019 03:09, Halil Pasic wrote:
> On Fri, 22 Feb 2019 16:29:56 +0100
> Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
>
> > We need to associate the ap_vfio_queue, which will hold the
> > per queue information for interrupt with a matrix mediated device
> > which hold the configuration and the way to the CRYCB.
> [..]
> > +static int vfio_ap_get_all_domains(struct ap_matrix_mdev *matrix_mdev, int apid)
> > +{
> > +	int apqi, apqn;
> > +	int ret = 0;
> > +	struct vfio_ap_queue *q;
> > +	struct list_head q_list;
> > +
> > +	INIT_LIST_HEAD(&q_list);
> > +
> > +	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) {
> > +		apqn = AP_MKQID(apid, apqi);
> > +		q = vfio_ap_get_queue(apqn, &matrix_dev->free_list);
> > +		if (!q) {
> > +			ret = -EADDRNOTAVAIL;
> > +			goto rewind;
> > +		}
> > +		if (q->matrix_mdev) {
> > +			ret = -EADDRINUSE;
>
> You tried to get the q from matrix_dev->free_list thus modulo races
> q->matrix_mdev should be 0. This change breaks the error codes in a
> sense that it becomes impossible to provoke EADDRINUSE (the proper
> error code for taken by another matrix_mdev).

right.
I will change this.

Regards,
Pierre

--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany