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Commit e2e004ac authored by Ross Lagerwall's avatar Ross Lagerwall Committed by David S. Miller
Browse files

xen-netfront: Improve error handling during initialization 



This fixes a crash when running out of grant refs when creating many
queues across many netdevs.

* If creating queues fails (i.e. there are no grant refs available),
call xenbus_dev_fatal() to ensure that the xenbus device is set to the
closed state.
* If no queues are created, don't call xennet_disconnect_backend as
netdev->real_num_tx_queues will not have been set correctly.
* If setup_netfront() fails, ensure that all the queues created are
cleaned up, not just those that have been set up.
* If any queues were set up and an error occurs, call
xennet_destroy_queues() to clean up the napi context.
* If any fatal error occurs, unregister and destroy the netdev to avoid
leaving around a half setup network device.

Signed-off-by: default avatarRoss Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1b5805c2

drivers/net/xen-netfront.c

+11 −18
Original line number Diff line number Diff line
@@ -1830,27 +1830,19 @@ static int talk_to_netback(struct xenbus_device *dev, 
		xennet_destroy_queues(info);



	err = xennet_create_queues(info, &num_queues);

	if (err < 0)

		goto destroy_ring;

	if (err < 0) {

		xenbus_dev_fatal(dev, err, "creating queues");

		kfree(info->queues);

		info->queues = NULL;

		goto out;

	}



	/* Create shared ring, alloc event channel -- for each queue */

	for (i = 0; i < num_queues; ++i) {

		queue = &info->queues[i];

		err = setup_netfront(dev, queue, feature_split_evtchn);

		if (err) {

			/* setup_netfront() will tidy up the current

			 * queue on error, but we need to clean up

			 * those already allocated.

			 */

			if (i > 0) {

				rtnl_lock();

				netif_set_real_num_tx_queues(info->netdev, i);

				rtnl_unlock();

		if (err)

			goto destroy_ring;

			} else {

				goto out;

			}

		}

	}



again:
@@ -1940,9 +1932,10 @@ static int talk_to_netback(struct xenbus_device *dev, 
	xenbus_transaction_end(xbt, 1);

 destroy_ring:

	xennet_disconnect_backend(info);

	kfree(info->queues);

	info->queues = NULL;

	xennet_destroy_queues(info);

 out:

	unregister_netdev(info->netdev);

	xennet_free_netdev(info->netdev);

	return err;

}