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Date: Fri, 6 Oct 2017 17:08:41 -0700 (PDT) From: Stefano Stabellini <sstabellini@...nel.org> To: Boris Ostrovsky <boris.ostrovsky@...cle.com> cc: Stefano Stabellini <sstabellini@...nel.org>, xen-devel@...ts.xen.org, linux-kernel@...r.kernel.org, jgross@...e.com, Stefano Stabellini <stefano@...reto.com> Subject: Re: [PATCH v4 02/13] xen/pvcalls: implement frontend disconnect On Wed, 20 Sep 2017, Boris Ostrovsky wrote: > > static int pvcalls_front_remove(struct xenbus_device *dev) > > { > > + struct pvcalls_bedata *bedata; > > + struct sock_mapping *map = NULL, *n; > > + > > + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); > > + dev_set_drvdata(&dev->dev, NULL); > > + pvcalls_front_dev = NULL; > > One more comment on this patch: should this be the last thing to do? > pvcalls_front_dev is what prevents pvcalls_front_probe() from proceeding > and even though I am not sure a probe can be initiated while we are here > perhaps moving this to the end would make things slightly safer. pvcalls_front_dev = NULL is set early to prevent most other functions (connect, listen, etc) from proceeding. On the other end, pvcalls_front_probe can continue safely in parallel with pvcalls_front_remove to add a new frontend-backend connection (which is not supported today anyway). pvcalls_front_probe would be called with a different xenbus_device parameter. > > + if (bedata->irq >= 0) > > + unbind_from_irqhandler(bedata->irq, dev); > > + > > + smp_mb(); > > + while (atomic_read(&pvcalls_refcount) > 0) > > + cpu_relax(); > > + list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) { > > + pvcalls_front_free_map(bedata, map); > > + kfree(map); > > + } > > + list_for_each_entry_safe(map, n, &bedata->socketpass_mappings, list) { > > + spin_lock(&bedata->socket_lock); > > + list_del_init(&map->list); > > + spin_unlock(&bedata->socket_lock); > > + kfree(map); > > + } > > + if (bedata->ref >= 0) > > + gnttab_end_foreign_access(bedata->ref, 0, 0); > > + kfree(bedata->ring.sring); > > + kfree(bedata); > > + xenbus_switch_state(dev, XenbusStateClosed); > > return 0; > > } > > >
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