From mboxrd@z Thu Jan 1 00:00:00 1970 From: Veaceslav Falico Subject: [PATCH v2 net-next] net: make dev_set_mtu() honor notification return code Date: Fri, 10 Jan 2014 16:56:25 +0100 Message-ID: <1389369385-17439-1-git-send-email-vfalico@redhat.com> Cc: Veaceslav Falico , Jiri Pirko , "David S. Miller" , Eric Dumazet , Alexander Duyck , Nicolas Dichtel To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:45203 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751620AbaAJQAv (ORCPT ); Fri, 10 Jan 2014 11:00:51 -0500 Sender: netdev-owner@vger.kernel.org List-ID: Currently, after changing the MTU for a device, dev_set_mtu() calls NETDEV_CHANGEMTU notification, however doesn't verify it's return code - which can be NOTIFY_BAD - i.e. some of the net notifier blocks refused this change, and continues nevertheless. To fix this, verify the return code, and if it's an error - then revert the MTU to the original one, notify again and pass the error code. CC: Jiri Pirko CC: "David S. Miller" CC: Eric Dumazet CC: Alexander Duyck CC: Nicolas Dichtel Signed-off-by: Veaceslav Falico --- Notes: v1 -> v2: Notify again after we've reverted the MTU back to the original, so that everyone has a chance to change its MTU back. net/core/dev.c | 34 +++++++++++++++++++++++++--------- 1 file changed, 25 insertions(+), 9 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index ce01847..0991d94 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5287,6 +5287,17 @@ int dev_change_flags(struct net_device *dev, unsigned int flags) } EXPORT_SYMBOL(dev_change_flags); +static int __dev_set_mtu(struct net_device *dev, int new_mtu) +{ + const struct net_device_ops *ops = dev->netdev_ops; + + if (ops->ndo_change_mtu) + return ops->ndo_change_mtu(dev, new_mtu); + + dev->mtu = new_mtu; + return 0; +} + /** * dev_set_mtu - Change maximum transfer unit * @dev: device @@ -5296,8 +5307,7 @@ EXPORT_SYMBOL(dev_change_flags); */ int dev_set_mtu(struct net_device *dev, int new_mtu) { - const struct net_device_ops *ops = dev->netdev_ops; - int err; + int err, orig_mtu; if (new_mtu == dev->mtu) return 0; @@ -5309,14 +5319,20 @@ int dev_set_mtu(struct net_device *dev, int new_mtu) if (!netif_device_present(dev)) return -ENODEV; - err = 0; - if (ops->ndo_change_mtu) - err = ops->ndo_change_mtu(dev, new_mtu); - else - dev->mtu = new_mtu; + orig_mtu = dev->mtu; + err = __dev_set_mtu(dev, new_mtu); - if (!err) - call_netdevice_notifiers(NETDEV_CHANGEMTU, dev); + if (!err) { + err = call_netdevice_notifiers(NETDEV_CHANGEMTU, dev); + err = notifier_to_errno(err); + if (err) { + /* setting mtu back and notifying everyone again, + * so that they have a chance to revert changes. + */ + __dev_set_mtu(dev, orig_mtu); + call_netdevice_notifiers(NETDEV_CHANGEMTU, dev); + } + } return err; } EXPORT_SYMBOL(dev_set_mtu); -- 1.8.4