From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754703AbdBHOfA (ORCPT ); Wed, 8 Feb 2017 09:35:00 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:34973 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753378AbdBHOev (ORCPT ); Wed, 8 Feb 2017 09:34:51 -0500 Subject: Re: [PATCH v3] xen-netfront: Improve error handling during initialization To: Ross Lagerwall , xen-devel@lists.xenproject.org References: <1486551457-25963-1-git-send-email-ross.lagerwall@citrix.com> Cc: netdev@vger.kernel.org, Juergen Gross , linux-kernel@vger.kernel.org, wei.liu2@citrix.com From: Boris Ostrovsky Message-ID: Date: Wed, 8 Feb 2017 09:34:51 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <1486551457-25963-1-git-send-email-ross.lagerwall@citrix.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/08/2017 05:57 AM, Ross Lagerwall wrote: > 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: Ross Lagerwall > --- > > Changed in V3: > * If xennet_create_queues returns < 0, it will not have created any > queues so there's no need to go to destroy_ring. > > drivers/net/xen-netfront.c | 29 +++++++++++------------------ > 1 file changed, 11 insertions(+), 18 deletions(-) > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 722fe9f..f90fc72 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -1823,27 +1823,19 @@ 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; > + } I think it might be better to kfree() in xennet_create_queues() (and set num_queues to zero, while at it). But either way: Reviewed-by: Boris Ostrovsky > > /* 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(); > - goto destroy_ring; > - } else { > - goto out; > - } > - } > + if (err) > + goto destroy_ring; > } > > again: > @@ -1933,9 +1925,10 @@ 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; > } >