Re: [PATCH net-next v8 10/10] net: airoha: Support multiple LAN/WAN interfaces for hw MAC address configuration

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Driver probe fails on systems where MAC addresses are randomly generated.
- [High] Configuration deadlock prevents users from changing the MAC address OUI.
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commit dbc4f298ffd475d67c32eeea98f201059b73194a
Author: Lorenzo Bianconi <lorenzo@kernel.org>

net: airoha: Support multiple LAN/WAN interfaces for hw MAC address configuration

The EN7581 and AN7583 SoCs provide registers to configure hardware LAN/WAN
MAC addresses. The hardware design assumes all interfaces configured as LAN
(or WAN) share a common upper MAC address. This patch extends the logic to
derive the correct minimum and maximum values when two or more interfaces
are configured.

> diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
> index 328f94fef2e28..9ae1ba4333097 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.c
> +++ b/drivers/net/ethernet/airoha/airoha_eth.c
> @@ -71,20 +71,69 @@ static void airoha_qdma_irq_disable(struct airoha_irq_bank *irq_bank,
>  	airoha_qdma_set_irqmask(irq_bank, index, mask, 0);
>  }
>  
> -static void airoha_set_macaddr(struct airoha_gdm_dev *dev, const u8 *addr)
> +static int airoha_set_macaddr(struct airoha_gdm_dev *dev, const u8 *addr)
>  {

[ ... ]

> +			if (netdev->reg_state != NETREG_REGISTERED)
> +				continue;
> +
> +			ether_addr_copy(ref_addr, netdev->dev_addr);
> +			val = (netdev->dev_addr[3] << 16) |
> +			      (netdev->dev_addr[4] << 8) | netdev->dev_addr[5];
> +			if (val < lmin)
> +				lmin = val;
> +			if (val > lmax)
> +				lmax = val;
> +		}
> +	}
> +
> +	if (!is_zero_ether_addr(ref_addr) && memcmp(ref_addr, addr, 3)) {

Does this strict OUI validation cause the driver probe to fail when MAC addresses
are randomly generated?

If a MAC address is not provided in the device tree, the driver generates a random
one via eth_hw_addr_random(). For multi-port configurations, each port receives an
independently generated random MAC address.

Since the upper 3 bytes of these random addresses will almost certainly differ,
when register_netdev() is called for the second port, its ndo_init callback
(airoha_dev_init) will invoke airoha_set_macaddr() and hit this check. Returning
-EINVAL will fail register_netdev() and abort the entire driver probe, leaving
the system without networking.

Does this also prevent users from changing the MAC address OUI?

When an administrator attempts to change the MAC address via standard userspace
tools, only one interface can be modified at a time. The driver will compare the
new MAC against the existing MAC of the other port.

If the MSBs differ, the change is rejected. This makes it impossible to atomically
change the OUI of both interfaces simultaneously, locking the MAC address OUI
to its initial probe-time value.

> +		/* According to the HW design, hw mac address MS bits
> +		 * must be the same for each net_device with the same
> +		 * LAN/WAN configuration.
> +		 */
> +		netdev_err(dev->dev, "wrong mac addr for shared GDM port\n");
> +		return -EINVAL;
> +	}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260519-airoha-eth-multi-serdes-v8-0-6bd70e329df6@kernel.org?part=10