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

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Message-ID: <20250219075515.1505887-1-liuhangbin@gmail.com>
Date: Wed, 19 Feb 2025 07:55:15 +0000
From: Hangbin Liu <liuhangbin@...il.com>
To: netdev@...r.kernel.org
Cc: Jay Vosburgh <jv@...sburgh.net>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Nikolay Aleksandrov <razor@...ckwall.org>,
	Simon Horman <horms@...nel.org>,
	linux-kernel@...r.kernel.org,
	Hangbin Liu <liuhangbin@...il.com>
Subject: [PATCH net-next] bonding: report duplicate MAC address in all situations

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@...il.com>
---
 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)