[PATCH net-next] bonding: report duplicate MAC address in all situations

From: Hangbin Liu
Date: Wed Feb 19 2025 - 02:55:39 EST


Normally, a bond uses the MAC address of the first added slave as the
bond’s MAC address. And the bond will set active slave’s MAC address to
bond’s address if fail_over_mac is set to none (0) or follow (2).

When the first slave is removed, the bond will still use the removed
slave’s MAC address, which can lead to a duplicate MAC address and
potentially cause issues with the switch. To avoid confusion, let's warn
the user in all situations, including when fail_over_mac is set to 2 or
in active-backup mode.

Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
---
drivers/net/bonding/bond_main.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index e45bba240cbc..ca66107776cc 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2551,13 +2551,11 @@ static int __bond_release_one(struct net_device *bond_dev,

RCU_INIT_POINTER(bond->current_arp_slave, NULL);

- if (!all && (!bond->params.fail_over_mac ||
- BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP)) {
- if (ether_addr_equal_64bits(bond_dev->dev_addr, slave->perm_hwaddr) &&
- bond_has_slaves(bond))
- slave_warn(bond_dev, slave_dev, "the permanent HWaddr of slave - %pM - is still in use by bond - set the HWaddr of slave to a different address to avoid conflicts\n",
- slave->perm_hwaddr);
- }
+ if (!all &&
+ ether_addr_equal_64bits(bond_dev->dev_addr, slave->perm_hwaddr) &&
+ bond_has_slaves(bond))
+ slave_warn(bond_dev, slave_dev, "the permanent HWaddr of slave - %pM - is still in use by bond - set the HWaddr of slave to a different address to avoid conflicts\n",
+ slave->perm_hwaddr);

if (rtnl_dereference(bond->primary_slave) == slave)
RCU_INIT_POINTER(bond->primary_slave, NULL);
--
2.39.5 (Apple Git-154)