>
>>> + ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
>>> XEN_9PFS_RING_ORDER);
>>> + if (ring->bytes == NULL)
>>> + goto error;
>>> + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
>>> + ring->intf->ref[i] =
>>> gnttab_grant_foreign_access(dev->otherend_id,
>>> pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);
>>> + ring->ref = gnttab_grant_foreign_access(dev->otherend_id,
>>> pfn_to_gfn(virt_to_pfn((void*)ring->intf)), 0);
>>> + ring->ring.in = ring->bytes;
>>> + ring->ring.out = ring->bytes + XEN_9PFS_RING_SIZE;
>>> +
>>> + ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
>>> + if (ret)
>>> + goto error;
>>> + ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
>>> xen_9pfs_front_event_handler,
>>> + 0, "xen_9pfs-frontend", ring);
>>> + if (ring->irq < 0) {
>>> + xenbus_free_evtchn(dev, ring->evtchn);
>>> + ret = ring->irq;
>>> + goto error;
>>> + }
>>> return 0;
>>> +
>>> +error:
>> You may need to gnttab_end_foreign_access().
> Actually this error path is unnecessary because it will be handled by
> xen_9pfs_front_probe, that calls xen_9pfs_front_free on errors. I'll
> remove it.
(It's a matter of personal preference but I think a routine should clean
up its own mess whenever it can.)
>
>
> +
> + 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, "num-rings", "%u",
> priv->num_rings);
> + if (ret)
> + goto error_xenbus;
> + for (i = 0; i < priv->num_rings; i++) {
> + char str[16];
> +
> + priv->rings[i].priv = priv;
> + ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]);
>> Not for -EAGAIN, I think.
> I don't think xen_9pfs_front_alloc_dataring can return EAGAIN. EAGAIN
> can only come from xenbus_transaction_end, the case we handle below.
I didn't mean that xen_9pfs_front_alloc_dataring() can return -EAGAIN. I
was referring to...
>
>
>>> + if (ret < 0)
>>> + goto error_xenbus;
>>> +
>>> + sprintf(str, "ring-ref%u", i);
>>> + ret = xenbus_printf(xbt, dev->nodename, str, "%d",
>>> priv->rings[i].ref);
>>> + if (ret)
>>> + goto error_xenbus;
>>> +
>>> + sprintf(str, "event-channel-%u", i);
>>> + ret = xenbus_printf(xbt, dev->nodename, str, "%u",
>>> priv->rings[i].evtchn);
>>> + if (ret)
>>> + goto error_xenbus;
>>> + }
>>> + priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
>>> + if (ret)
>>> + goto error_xenbus;
>>> + ret = xenbus_transaction_end(xbt, 0);
>>> + if (ret) {
>>> + if (ret == -EAGAIN)
>>> + goto again;
... this.
Sorry for not being clear.
-boris
