Patch "bonding: correct the MAC address for "follow" fail_over_mac policy" has been added to the 3.10-stable tree

This is a note to let you know that I've just added the patch titled

bonding: correct the MAC address for "follow" fail_over_mac policy

to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
bonding-correct-the-mac-address-for-follow-fail_over_mac-policy.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: dingtianhong <[email protected]>
Date: Thu, 16 Jul 2015 16:30:02 +0800
Subject: bonding: correct the MAC address for "follow" fail_over_mac policy

From: dingtianhong <[email protected]>

[ Upstream commit a951bc1e6ba58f11df5ed5ddc41311e10f5fd20b ]

The "follow" fail_over_mac policy is useful for multiport devices that either become confused or incur a performance penalty when multiple ports are programmed with the same MAC address, but the same MAC address still may happened by this steps for this policy:

1) echo +eth0 > /sys/class/net/bond0/bonding/slaves bond0 has the same mac address with eth0, it is MAC1.

2) echo +eth1 > /sys/class/net/bond0/bonding/slaves eth1 is backup, eth1 has MAC2.

3) ifconfig eth0 down
eth1 became active slave, bond will swap MAC for eth0 and eth1, so eth1 has MAC1, and eth0 has MAC2.

4) ifconfig eth1 down
there is no active slave, and eth1 still has MAC1, eth2 has MAC2.

5) ifconfig eth0 up
the eth0 became active slave again, the bond set eth0 to MAC1.

Something wrong here, then if you set eth1 up, the eth0 and eth1 will have the same MAC address, it will break this policy for ACTIVE_BACKUP mode.

This patch will fix this problem by finding the old active slave and swap them MAC address before change active slave.

---
 drivers/net/bonding/bond_main.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

@@ -876,6 +876,23 @@ static void bond_mc_swap(struct bonding
 	}
 }
 
+static struct slave *bond_get_old_active(struct bonding *bond,
+					 struct slave *new_active)
+{
+	struct slave *slave;
+	int i;
+
+	bond_for_each_slave(bond, slave, i) {
+		if (slave == new_active)
+			continue;
+
+		if (ether_addr_equal(bond->dev->dev_addr, slave->dev->dev_addr))
+			return slave;
+	}
+
+	return NULL;
+}
+
 /*
  * bond_do_fail_over_mac
  *

@@ -919,6 +936,9 @@ static void bond_do_fail_over_mac(struct
 		write_unlock_bh(&bond->curr_slave_lock);
 		read_unlock(&bond->lock);
 
+		if (!old_active)
+			old_active = bond_get_old_active(bond, new_active);
+
 		if (old_active) {
 			memcpy(tmp_mac, new_active->dev->dev_addr, ETH_ALEN);
 			memcpy(saddr.sa_data, old_active->dev->dev_addr,

Patches currently in stable-queue which might be from [email protected] are

queue-3.10/bonding-correct-the-mac-address-for-follow-fail_over_mac-policy.patch