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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 <jiri@resnulli.us>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Veaceslav Falico 2014-01-10 16:56:25 +01:00 committed by David S. Miller
parent 7e11daa7c1
commit 2315dc91a5
1 changed files with 25 additions and 9 deletions
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34
net/core/dev.c
View File

@ -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);