On Fri, Jul 03, 2026 at 03:39:36PM +0800, Hanson Wang wrote:

aqc111_set_mac_addr() returns the result of aqc111_write_cmd() on
success. That function wraps usb_control_msg(), which returns the
number of bytes transferred (6 for ETH_ALEN) rather than zero.

Bonding calls ndo_set_mac_address() when enslaving an interface and
treats any non-zero return value as failure.

It is not just bonding which has problems:

int netif_set_mac_address(struct net_device *dev, struct sockaddr_storage *ss,
			  struct netlink_ext_ack *extack)
{
	const struct net_device_ops *ops = dev->netdev_ops;
	int err;

	if (!ops->ndo_set_mac_address)
		return -EOPNOTSUPP;
	if (ss->ss_family != dev->type)
		return -EINVAL;
	if (!netif_device_present(dev))
		return -ENODEV;
	err = netif_pre_changeaddr_notify(dev, ss->__data, extack);
	if (err)
		return err;
	if (memcmp(dev->dev_addr, ss->__data, dev->addr_len)) {
		err = ops->ndo_set_mac_address(dev, ss);
		if (err)
			return err;

Could you take a quick look at all USB ethernet drivers, and see if
this bug exists in other drivers. If one driver has it wrong, it could
well be more have it wrong.

     Andrew