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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Nikolay Aleksandrov , Simon Horman , Shuah Khan , linux-kselftest@vger.kernel.org, Qiuling Ren Subject: Re: [PATCH net 1/2] bonding: set random address only when slaves already exist Message-ID: References: <20250820091009.393785-1-liuhangbin@gmail.com> <1546564.1755908490@famine> <2918806.1757449543@famine> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2918806.1757449543@famine> 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: 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: 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: 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: 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: 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: 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