Re: [RFC net-next] bonding: Retry updating slave MAC after a failure

[Jay Vosburgh <jv@jvosburgh.net>]

Paritosh Potukuchi <paritoshpotukuchi@gmail.com> wrote:

>> I think the proper thing to do is remove this comment block and
>make no other changes.
>
>  > This comment dates to sometime before git, when it was common
>for network device drivers to lack the ability to change the MAC while
>the interface is up.  To the best of my knowledge, that isn't a issue
>today.
>
>Sure Jay. That makes sense. Should I go ahead and post a patch 
>removing this comment?

	Yes, please do so.

	-J

>  -Paritosh
>
>On Wed, 1 Jul 2026 at 04:29, Jay Vosburgh <jv@jvosburgh.net> wrote:
>
>    Paritosh Potukuchi <paritoshpotukuchi@gmail.com> wrote:
>
>    >I came across this TODO in bond_set_mac_address() :
>    >
>    >        /* TODO: consider downing the slave
>    >         * and retry ?
>    >         * User should expect communications
>    >         * breakage anyway until ARP finish
>    >         * updating, so...
>    >         */
>    >
>    >Currently, if the dev_set_mac_address() fails on a slave, we go
>    >ahead and unwind the bond and its slaves.
>    >
>    >As the TODO suggests, one possible solution is to try setting
>    >the MAC again, after putting down the interface. This is because some
>    >drivers may reject changing the MAC when the device is UP.
>    >
>    >The solution I am proposing is as follows:
>    >
>    >dev_set_mac_address on the slave
>    >        - If this fails, temporarily stop the slave - ndo_stop
>    >                - If stop fails, unwind
>    >        - call dev_set_mac_address() on the slave
>    >                - If this fails, unwind
>    >        - Bring up the slave by calling ndo_open
>    >                - If this fails, unwind
>    >If dev_set_mac_address on slave passes, we go to the next slave
>    >
>    >
>    >Before working on a patch, I wanted to get feedback on whether
>    >this interpretation of the TODO makes sense and whether there
>    >are concerns with temporarily stopping and restarting a slave
>    >during bond_set_mac_address().
>
>            I think the proper thing to do is remove this comment block
>    and
>    make no other changes.
>
>            This comment dates to sometime before git, when it was common
>    for network device drivers to lack the ability to change the MAC while
>    the interface is up.  To the best of my knowledge, that isn't a issue
>    today.
>
>            -J
>

---
	-Jay Vosburgh, jv@jvosburgh.net