netdev - Re: [PATCH net-next 1/6] ethernet: add a helper for assigning port addresses

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Message-ID: <33fba14b-01cb-8644-7678-a0f12d9cf499@pensando.io>
Date:   Mon, 18 Oct 2021 14:54:49 -0700
From:   Shannon Nelson <snelson@...sando.io>
To:     Jakub Kicinski <kuba@...nel.org>, davem@...emloft.net
Cc:     netdev@...r.kernel.org, olteanv@...il.com, andrew@...n.ch,
        idosch@...sch.org, f.fainelli@...il.com
Subject: Re: [PATCH net-next 1/6] ethernet: add a helper for assigning port
 addresses

On 10/18/21 2:10 PM, Jakub Kicinski wrote:
> We have 5 drivers which offset base MAC addr by port id.
> Create a helper for them.
>
> This helper takes care of overflows, which some drivers
> did not do, please complain if that's going to break
> anything!
>
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>

Reviewed-by: Shannon Nelson <snelson@...sando.io>


> --
>   - eth_hw_addr_set_port() -> eth_hw_addr_gen()
>   - id u8 -> unsigned int
> ---
>   include/linux/etherdevice.h | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
>
> diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
> index 23681c3d3b8a..2ad71cc90b37 100644
> --- a/include/linux/etherdevice.h
> +++ b/include/linux/etherdevice.h
> @@ -551,6 +551,27 @@ static inline unsigned long compare_ether_header(const void *a, const void *b)
>   #endif
>   }
>   
> +/**
> + * eth_hw_addr_gen - Generate and assign Ethernet address to a port
> + * @dev: pointer to port's net_device structure
> + * @base_addr: base Ethernet address
> + * @id: offset to add to the base address
> + *
> + * Generate a MAC address using a base address and an offset and assign it
> + * to a net_device. Commonly used by switch drivers which need to compute
> + * addresses for all their ports. addr_assign_type is not changed.
> + */
> +static inline void eth_hw_addr_gen(struct net_device *dev, const u8 *base_addr,
> +				   unsigned int id)
> +{
> +	u64 u = ether_addr_to_u64(base_addr);
> +	u8 addr[ETH_ALEN];
> +
> +	u += id;
> +	u64_to_ether_addr(u, addr);
> +	eth_hw_addr_set(dev, addr);
> +}
> +
>   /**
>    * eth_skb_pad - Pad buffer to mininum number of octets for Ethernet frame
>    * @skb: Buffer to pad