Messages in this thread | | | Subject | Re: [PATCH v4 3/7] s390: ap: associate a ap_vfio_queue and a matrix mdev | From | Pierre Morel <> | Date | Wed, 13 Mar 2019 11:19:52 +0100 |
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On 12/03/2019 22:39, Tony Krowiak wrote: > On 3/3/19 9:09 PM, Halil Pasic wrote: >> On Fri, 22 Feb 2019 16:29:56 +0100 >> Pierre Morel <pmorel@linux.ibm.com> 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). > > It is necessary to determine if the queue is in use by another mdev, so > it will still be necessary to traverse all of the matrix_mdev structs to > see if q is in matrix_mdev->qlist. It seems that maintaining the qlist > does not buy us much. >
Tony, Halil already pointed out this issue and I already answered. Please, no need to duplicate the remarks.
Pierre
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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