On Tue, Sep 09, 2025 at 01:25:43PM -0700, Jay Vosburgh wrote:
> >>
> >> Sorry I didn't make it clear. A easy reproducer would describe the issue.
> >> e.g.
> >> (omit the lo interface)
> >>
> >> [root@virtme-ng net]# ip link add type veth
> >> [root@virtme-ng net]# ip link add bond0 type bond mode 1 miimon 100
> >> fail_over_mac 2
> >> [root@virtme-ng net]# ip link show
> >> 3: veth0@veth1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state
> >> DOWN mode DEFAULT group default qlen 1000
> >> link/ether 02:0a:04:c2:d6:21 brd ff:ff:ff:ff:ff:ff
> >> 4: veth1@veth0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state
> >> DOWN mode DEFAULT group default qlen 1000
> >> link/ether 82:a8:52:f4:81:4e brd ff:ff:ff:ff:ff:ff
> >> 5: bond0: <BROADCAST,MULTICAST,MASTER> mtu 1500 qdisc noop state DOWN mode
> >> DEFAULT group default qlen 1000
> >> link/ether 92:5d:9c:47:e7:53 brd ff:ff:ff:ff:ff:ff
> >> [root@virtme-ng net]# ip link set veth0 master bond0
> >> [root@virtme-ng net]# ip link show
> >> 3: veth0@veth1: <NO-CARRIER,BROADCAST,MULTICAST,SLAVE,UP,M-DOWN> mtu 1500
> >> qdisc noqueue master bond0 state LOWERLAYERDOWN mode DEFAULT group default
> >> qlen 1000
> >> link/ether 4e:b5:4a:b4:03:18 brd ff:ff:ff:ff:ff:ff
> >> 4: veth1@veth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode
> >> DEFAULT group default qlen 1000
> >> link/ether 82:a8:52:f4:81:4e brd ff:ff:ff:ff:ff:ff
> >> 5: bond0: <BROADCAST,MULTICAST,MASTER> mtu 1500 qdisc noop state DOWN mode
> >> DEFAULT group default qlen 1000
> >> link/ether 02:0a:04:c2:d6:21 brd ff:ff:ff:ff:ff:ff
> >>
> >> Here we can see the veth0's mac address is randomized. The reason is in
> >> function bond_enslave(), we set the bond mac address to the same as slave's
> >> if it's the first one.
> >>
> >> /* If this is the first slave, then we need to set the master's
> >> hardware
> >> * address to be the same as the slave's.
> >> */
> >> if (!bond_has_slaves(bond) &&
> >> bond->dev->addr_assign_type == NET_ADDR_RANDOM) {
> >> res = bond_set_dev_addr(bond->dev, slave_dev);
> >> if (res)
> >> goto err_undo_flags;
> >> }
> >>
> >> And later
> >>
> >> } else if (bond->params.fail_over_mac == BOND_FOM_FOLLOW &&
> >> BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP &&
> >> 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.
> >> */
> >> eth_random_addr(ss.__data);
> >> } else {
> >>
> >> Here we check the bond and slave's mac address, which would be the same
> >> definitely, which cause the first slave's mac got changed.
> >
> >Any comments for this?
>
> Sorry, fell off the radar.
>
> I follow what's going on now, and it's actually a lot simpler
> than the description suggests, at least to my reading. Perhaps language
> like:
>
> 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.
>
> Does that sound ok to you?
Sure. As a non native English speaker, I always struggle to organize the patch
description. Thanks for your update.
Regards
Hangbin
