On Sat, 14 Mar 2009 10:49:11 +0100
Jiri Pirko [off-list ref] wrote:

Sat, Mar 14, 2009 at 06:39:32AM CET, shemminger@linux-foundation.org wrote:

quoted

On Fri, 13 Mar 2009 19:33:04 +0100
Jiri Pirko [off-list ref] wrote:

quoted

Hi all.

This is only a draft of patch to consult. I'm aware that it should be divided
into multiple patches. I want to know opinion from you folks.

The problem is described in following bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=487763

Basically here's what's going on. In every mode, bonding interface uses the same
mac address for all enslaved devices. Except for mode balance-alb. When you put
this kind of bond device into a bridge it will only add one of mac adresses into
a hash list of mac addresses, say X. This mac address is marked as local. But
this bonding interface also has mac address Y. Now then packet arrives with
destination address Y, this address is not marked as local and the packed looks
like it needs to be forwarded. This packet is then lost which is wrong.

Notice that interfaces can be added and removed from bond while it is in bridge.
Therefore I introduce another function pointer in struct net_device_ops -
ndo_check_mac_address. This function when it's implemented should check passed
mac address against the one set in device. I'm using this in bonding driver when
the bond is in mode balance-alb to walk thru all slaves and checking if any of
them equals passed address.

Then in bridge function br_handle_frame_finish() I'm using ndo_check_mac_address
to recognize the destination mac address as local.

Please look at this and tell me what you think about it.

Thanks

Jirka

A better and more general way to do this have the dev_set_mac_address
function check the return of the notifier and unwind. Then any protocol
can easily prevent address from changing.

Can you please describe this thougth a bit more? I can't understand it now...

Thanks

Jirka

Something like this:

--- a/net/core/dev.c	2009-03-15 15:55:02.098126056 -0700
+++ b/net/core/dev.c	2009-03-15 16:02:43.999251305 -0700

@@ -3830,6 +3830,7 @@ int dev_set_mac_address(struct net_devic
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
 	int err;
+	char save_addr[MAX_ADDR_LEN];
 
 	if (!ops->ndo_set_mac_address)
 		return -EOPNOTSUPP;

@@ -3837,9 +3838,17 @@ int dev_set_mac_address(struct net_devic
 		return -EINVAL;
 	if (!netif_device_present(dev))
 		return -ENODEV;
+
+	memcpy(save_addr, dev->dev_addr, dev->addr_len);
 	err = ops->ndo_set_mac_address(dev, sa);
-	if (!err)
-		call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
+	if (err)
+		return err;
+
+	err = call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
+	if (err) {
+		memcpy(sa->sa_data, save_addr, dev->addr_len);
+		ops->ndo_set_mac_address(dev, sa);
+	}
 	return err;
 }
 

And something like this:

--- a/drivers/net/bonding/bond_main.c	2009-03-15 16:03:53.909000973 -0700
+++ b/drivers/net/bonding/bond_main.c	2009-03-15 16:11:43.227127031 -0700

@@ -3534,6 +3534,7 @@ static int bond_slave_netdev_event(unsig
 {
 	struct net_device *bond_dev = slave_dev->master;
 	struct bonding *bond = netdev_priv(bond_dev);
+	int err;
 
 	switch (event) {
 	case NETDEV_UNREGISTER:

@@ -3570,6 +3571,15 @@ static int bond_slave_netdev_event(unsig
 		 * servitude.
 		 */
 		break;
+	case NETDEV_CHANGEADDR:
+		if (bond->params.mode == BOND_MODE_ALB)
+			err = bond_alb_check_mac_address(bond);
+		else if (compare_ether_addr(bond_dev->dev_addr, addr) != 0)
+			err = -EINVAL;
+
+		if (err)
+			return notifier_from_errno(err);
+		break;
 	case NETDEV_CHANGENAME:
 		/*
 		 * TODO: handle changing the primary's name