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SubjectRe: [PATCH v2 02/13] xen/pvcalls: connect to the backend
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>>> static int pvcalls_front_probe(struct xenbus_device *dev,
>>> const struct xenbus_device_id *id)
>>> {
>>> + int ret = -EFAULT, evtchn, ref = -1, i;
>>> + unsigned int max_page_order, function_calls, len;
>>> + char *versions;
>>> + grant_ref_t gref_head = 0;
>>> + struct xenbus_transaction xbt;
>>> + struct pvcalls_bedata *bedata = NULL;
>>> + struct xen_pvcalls_sring *sring;
>>> +
>>> + if (pvcalls_front_dev != NULL) {
>>> + dev_err(&dev->dev, "only one PV Calls connection
>>> supported\n");
>>> + return -EINVAL;
>>> + }
>>> +
>>> + versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
>>> + if (!len)
>>> + return -EINVAL;
>>> + if (strcmp(versions, "1")) {
>>> + kfree(versions);
>>> + return -EINVAL;
>>> + }
>>> + kfree(versions);
>>> + ret = xenbus_scanf(XBT_NIL, dev->otherend,
>>> + "max-page-order", "%u", &max_page_order);
>>> + if (ret <= 0)
>>> + return -ENODEV;
>>> + if (max_page_order < RING_ORDER)
>>> + return -ENODEV;
>>> + ret = xenbus_scanf(XBT_NIL, dev->otherend,
>>> + "function-calls", "%u", &function_calls);
>>> + if (ret <= 0 || function_calls != 1)
>>> + return -ENODEV;
>>> + pr_info("%s max-page-order is %u\n", __func__, max_page_order);
>>> +
>>> + bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
>>> + if (!bedata)
>>> + return -ENOMEM;
>>> +
>>> + init_waitqueue_head(&bedata->inflight_req);
>>> + for (i = 0; i < PVCALLS_NR_REQ_PER_RING; i++)
>>> + bedata->rsp[i].req_id = PVCALLS_INVALID_ID;
>>> +
>>> + sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
>>> + __GFP_ZERO);
>>> + if (!sring)
>>> + goto error;
>>> + SHARED_RING_INIT(sring);
>>> + FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);
>>> +
>>> + ret = xenbus_alloc_evtchn(dev, &evtchn);
>>> + if (ret)
>>> + goto error;
>>> +
>>> + bedata->irq = bind_evtchn_to_irqhandler(evtchn,
>>> + pvcalls_front_event_handler,
>>> + 0, "pvcalls-frontend", dev);
>>> + if (bedata->irq < 0) {
>>> + ret = bedata->irq;
>>> + goto error;
>>> + }
>>> +
>>> + ret = gnttab_alloc_grant_references(1, &gref_head);
>>> + if (ret < 0)
>>> + goto error;
>>> + bedata->ref = ref = gnttab_claim_grant_reference(&gref_head);
>> Is ref really needed?
> No, I'll remove it
>
>
>>> + if (ref < 0)
>>> + goto error;
>>> + gnttab_grant_foreign_access_ref(ref, dev->otherend_id,
>>> + virt_to_gfn((void *)sring), 0);
>>> +
>>> + again:
>>> + ret = xenbus_transaction_start(&xbt);
>>> + if (ret) {
>>> + xenbus_dev_fatal(dev, ret, "starting transaction");
>>> + goto error;
>>> + }
>>> + ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
>>> + if (ret)
>>> + goto error_xenbus;
>>> + ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
>>> + if (ret)
>>> + goto error_xenbus;
>>> + ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
>>> + evtchn);
>>> + if (ret)
>>> + goto error_xenbus;
>>> + ret = xenbus_transaction_end(xbt, 0);
>>> + if (ret) {
>>> + if (ret == -EAGAIN)
>>> + goto again;
>>> + xenbus_dev_fatal(dev, ret, "completing transaction");
>>> + goto error;
>>> + }
>>> +
>>> + INIT_LIST_HEAD(&bedata->socket_mappings);
>>> + INIT_LIST_HEAD(&bedata->socketpass_mappings);
>>> + spin_lock_init(&bedata->pvcallss_lock);
>>> + dev_set_drvdata(&dev->dev, bedata);
>>> + pvcalls_front_dev = dev;
>>> + xenbus_switch_state(dev, XenbusStateInitialised);
>>> +
>>> return 0;
>>> +
>>> + error_xenbus:
>>> + xenbus_transaction_end(xbt, 1);
>>> + xenbus_dev_fatal(dev, ret, "writing xenstore");
>>> + error:
>>> + pvcalls_front_remove(dev);
>> I think patch 12 (where you implement cleanup) could be moved before this one.
> I'll move the patch
>
>
>> I also think you are leaking bedata on error paths.
> bedata is freed by pvcalls_front_remove (kfree(bedata)), why do you say
> so?

bedata there is read from dev_get_drvdata() and here you assign drvdata
at the very end.

Come think of it, pvcalls_front_remove() should probably first check
whether bedata is valid. Or drvdata should be assigned right away in
this routine, before any 'got error/error_xenbus'.

-boris

>
>
>>> + return ret;
>>> }
>>>

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