From 2315dc91a5059d7da9a8b9b9daf78d695c11383e Mon Sep 17 00:00:00 2001 From: Veaceslav Falico Date: Fri, 10 Jan 2014 16:56:25 +0100 Subject: net: make dev_set_mtu() honor notification return code 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 Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller --- net/core/dev.c | 34 +++++++++++++++++++++++++--------- 1 file changed, 25 insertions(+), 9 deletions(-) (limited to 'net/core') diff --git a/net/core/dev.c b/net/core/dev.c index a8280154c42a..87312dcf0aa8 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5300,6 +5300,17 @@ 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 @@ -5309,8 +5320,7 @@ 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; @@ -5322,14 +5332,20 @@ 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); -- cgit v1.2.3