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Commit 2315dc91 authored by Veaceslav Falico's avatar Veaceslav Falico Committed by David S. Miller
Browse files

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: default avatarVeaceslav Falico <vfalico@redhat.com>
Reviewed-by: default avatarJiri Pirko <jiri@resnulli.us>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7e11daa7

net/core/dev.c

+25 −9
Original line number Diff line number Diff line
@@ -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)

	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);