From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH 4/6] netdev: allow rejecting MTU changes from notifiers Date: Fri, 17 Oct 2008 21:32:56 -0700 Message-ID: <20081018043323.642235776@vyatta.com> References: <20081018043252.968940967@vyatta.com> Cc: bonding-devel@lists.sourceforge.net, netdev@vger.kernel.org To: Jay Vousburgh Return-path: Received: from suva.vyatta.com ([76.74.103.44]:52219 "EHLO suva.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751208AbYJREgB (ORCPT ); Sat, 18 Oct 2008 00:36:01 -0400 Content-Disposition: inline; filename=dev-mtu-rollback.patch Sender: netdev-owner@vger.kernel.org List-ID: This patch allows notifiers to reject changes to MTU, and then does rollback same way change name does). Signed-off-by: Stephen Hemminger --- a/net/core/dev.c 2008-10-17 18:59:11.000000000 -0700 +++ b/net/core/dev.c 2008-10-17 21:22:30.000000000 -0700 @@ -3453,9 +3453,10 @@ int dev_change_flags(struct net_device * */ int dev_set_mtu(struct net_device *dev, int new_mtu) { - int err; + int ret, err = 0; + int old_mtu = dev->mtu; - if (new_mtu == dev->mtu) + if (new_mtu == old_mtu) return 0; /* MTU must be positive. */ @@ -3465,13 +3466,31 @@ int dev_set_mtu(struct net_device *dev, if (!netif_device_present(dev)) return -ENODEV; - err = 0; - if (dev->change_mtu) - err = dev->change_mtu(dev, new_mtu); - else +rollback: + if (dev->change_mtu) { + ret = dev->change_mtu(dev, new_mtu); + if (ret) + return ret; + } else dev->mtu = new_mtu; - if (!err && dev->flags & IFF_UP) - call_netdevice_notifiers(NETDEV_CHANGEMTU, dev); + + if (!err && (dev->flags & IFF_UP)) { + ret = call_netdevice_notifiers(NETDEV_CHANGEMTU, dev); + ret = notifier_to_errno(ret); + printk(KERN_DEBUG "dev_set_mtu notifier ret %d\n", ret); + + if (ret) { + if (err) { + printk(KERN_ERR "%s: mtu rollback failed: %d\n", + dev->name, ret); + } else { + err = ret; + new_mtu = old_mtu; + goto rollback; + } + } + + } return err; } --