Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

>  
> +static int xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
> +{
> +     int i, j;
> +
> +     list_del(&priv->list);
> +
> +     for (i = 0; i < priv->num_rings; i++) {
> +             if (priv->rings[i].intf == NULL)
> +                     break;

Are we guaranteed that all subsequent entries are not allocated (i.e.
this shouldn't be 'continue')?

> +             if (priv->rings[i].irq > 0)
> +                     unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
> +             if (priv->rings[i].bytes != NULL) {
> +                     for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++)
> +                             
> gnttab_end_foreign_access(priv->rings[i].intf->ref[j], 0, 0);
> +                     free_pages((unsigned long)priv->rings[i].bytes, 
> XEN_9PFS_RING_ORDER);
> +             }
> +             gnttab_end_foreign_access(priv->rings[i].ref, 0, 0);
> +             free_page((unsigned long)priv->rings[i].intf);
> +     }
> +     kfree(priv->rings);
> +     kfree(priv);
> +
> +     return 0;
> +}
> +
>  static int xen_9pfs_front_remove(struct xenbus_device *dev)
>  {
> +     int ret;
> +     struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
> +
> +     dev_set_drvdata(&dev->dev, NULL);
> +     ret = xen_9pfs_front_free(priv);
> +     return ret;
> +}
> +
> +static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
> +             struct xen_9pfs_dataring *ring)
> +{
> +     int i;
> +     int ret = -ENOMEM;
> +
> +     init_waitqueue_head(&ring->wq);
> +     spin_lock_init(&ring->lock);
> +     INIT_WORK(&ring->work, p9_xen_response);
> +
> +     ring->intf = (struct xen_9pfs_data_intf *) __get_free_page(GFP_KERNEL | 
> __GFP_ZERO);
> +     if (!ring->intf)
> +             goto error;
> +     memset(ring->intf, 0, XEN_PAGE_SIZE);

get_zeroed_page()?  (especially given that __get_free_page() returns
PAGE_SIZE, not XEN_PAGE_SIZE)


> +     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().

> +     if (ring->intf != NULL)
> +             kfree(ring->intf);
> +     if (ring->bytes != NULL)
> +             kfree(ring->bytes);
> +     return ret;
>  }
>  
>  static int xen_9pfs_front_probe(struct xenbus_device *dev,
>               const struct xenbus_device_id *id)
>  {
> +     int ret = -EFAULT, i;

Unnecessary initialization.

> +     struct xenbus_transaction xbt;
> +     struct xen_9pfs_front_priv *priv = NULL;
> +     char *versions;
> +     unsigned int max_rings, max_ring_order, len;
> +
> +     versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
> +     if (!len || strcmp(versions, "1"))
> +             return -EINVAL;
> +     kfree(versions);
> +     ret = xenbus_scanf(XBT_NIL, dev->otherend, "max-rings", "%u", 
> &max_rings);
> +     if (ret < 0 || max_rings < XEN_9PFS_NUM_RINGS)
> +             return -EINVAL;
> +     ret = xenbus_scanf(XBT_NIL, dev->otherend, "max-ring-page-order", "%u", 
> &max_ring_order);
> +     if (ret < 0|| max_ring_order < XEN_9PFS_RING_ORDER)
> +             return -EINVAL;
> +
> +
> +     priv = kzalloc(sizeof(struct xen_9pfs_front_priv), GFP_KERNEL);
> +     if (!priv)
> +             return -ENOMEM;
> +
> +     priv->dev = dev;
> +     priv->num_rings = XEN_9PFS_NUM_RINGS;
> +     priv->rings = kzalloc(sizeof(struct xen_9pfs_dataring) * 
> priv->num_rings,
> +                                             GFP_KERNEL);
> +     if (!priv->rings) {
> +             kfree(priv);
> +             return -ENOMEM;
> +     }
> +
> + 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.


-boris

> +             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;
> +             xenbus_dev_fatal(dev, ret, "completing transaction");
> +             goto error;
> +     }
> +
> +
> +     list_add_tail(&priv->list, &xen_9pfs_devs);
> +     dev_set_drvdata(&dev->dev, priv);
> +     xenbus_switch_state(dev, XenbusStateInitialised);
> +
>       return 0;
> +
> + error_xenbus:
> +     xenbus_transaction_end(xbt, 1);
> +     xenbus_dev_fatal(dev, ret, "writing xenstore");
> + error:
> +     dev_set_drvdata(&dev->dev, NULL);
> +     xen_9pfs_front_free(priv);
> +     return ret;
>  }
>  


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