netdev - Re: [PATCH net-next 1/3] iavf: add check for current MAC address in set

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Date: Mon, 5 Jun 2023 21:02:52 +0200
From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To: Tony Nguyen <anthony.l.nguyen@...el.com>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<edumazet@...gle.com>, <netdev@...r.kernel.org>, Piotr Gardocki
	<piotrx.gardocki@...el.com>, Michal Swiatkowski
	<michal.swiatkowski@...ux.intel.com>, Rafal Romanowski
	<rafal.romanowski@...el.com>
Subject: Re: [PATCH net-next 1/3] iavf: add check for current MAC address in
 set_mac callback

On Fri, Jun 02, 2023 at 10:13:00AM -0700, Tony Nguyen wrote:
> From: Piotr Gardocki <piotrx.gardocki@...el.com>
> 
> In some cases it is possible for kernel to come with request
> to change primary MAC address to the address that is actually
> already set on the given interface.
> 
> If the old and new MAC addresses are equal there is no need
> for going through entire routine, including AdminQ and
> waitqueue.
> 
> This patch adds proper check to return fast from the function
> in these cases. The same check can also be found in i40e and
> ice drivers.

couldn't this be checked the layer above then? and pulled out of drivers?

> 
> An example of such case is adding an interface to bonding
> channel in balance-alb mode:
> modprobe bonding mode=balance-alb miimon=100 max_bonds=1
> ip link set bond0 up
> ifenslave bond0 <eth>
> 
> Signed-off-by: Piotr Gardocki <piotrx.gardocki@...el.com>
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
> Tested-by: Rafal Romanowski <rafal.romanowski@...el.com>
> Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
> ---
>  drivers/net/ethernet/intel/iavf/iavf_main.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
> index 2de4baff4c20..420aaca548a0 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
> +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
> @@ -1088,6 +1088,12 @@ static int iavf_set_mac(struct net_device *netdev, void *p)
>  	if (!is_valid_ether_addr(addr->sa_data))
>  		return -EADDRNOTAVAIL;
>  
> +	if (ether_addr_equal(netdev->dev_addr, addr->sa_data)) {
> +		netdev_dbg(netdev, "already using mac address %pM\n",
> +			   addr->sa_data);

i am not sure if this is helpful message, you end up with an address that
you requested, why would you care that it was already same us you wanted?

> +		return 0;
> +	}
> +
>  	ret = iavf_replace_primary_mac(adapter, addr->sa_data);
>  
>  	if (ret)
> -- 
> 2.38.1
> 
>