netdev - [PATCHv2 net 1/2] bonding: set random address only when slaves already exist

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Message-ID: <20250910024336.400253-1-liuhangbin@gmail.com>
Date: Wed, 10 Sep 2025 02:43:34 +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>,
	Simon Horman <horms@...nel.org>,
	Shuah Khan <shuah@...nel.org>,
	linux-kselftest@...r.kernel.org,
	Hangbin Liu <liuhangbin@...il.com>,
	Qiuling Ren <qren@...hat.com>
Subject: [PATCHv2 net 1/2] bonding: set random address only when slaves already exist

After commit 5c3bf6cba791 ("bonding: assign random address if device
address is same as bond"), bonding will erroneously randomize the MAC
address of the first interface added to the bond if fail_over_mac =
follow.

Correct this by additionally testing for the bond being empty before
randomizing the MAC.

Fixes: 5c3bf6cba791 ("bonding: assign random address if device address is same as bond")
Reported-by: Qiuling Ren <qren@...hat.com>
Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
---
 drivers/net/bonding/bond_main.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 257333c88710..8832bc9f107b 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2132,6 +2132,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 		memcpy(ss.__data, bond_dev->dev_addr, bond_dev->addr_len);
 	} else if (bond->params.fail_over_mac == BOND_FOM_FOLLOW &&
 		   BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP &&
+		   bond_has_slaves(bond) &&
 		   memcmp(slave_dev->dev_addr, bond_dev->dev_addr, bond_dev->addr_len) == 0) {
 		/* Set slave to random address to avoid duplicate mac
 		 * address in later fail over.
-- 
2.50.1