netdev - Re: [PATCH net-next v2 1/3] net: add check for current MAC address in dev_set_mac

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Date: Tue, 13 Jun 2023 15:10:56 +0200
From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To: Piotr Gardocki <piotrx.gardocki@...el.com>
CC: <netdev@...r.kernel.org>, <intel-wired-lan@...ts.osuosl.org>,
	<przemyslaw.kitszel@...el.com>, <michal.swiatkowski@...ux.intel.com>,
	<pmenzel@...gen.mpg.de>, <kuba@...nel.org>, <anthony.l.nguyen@...el.com>,
	<simon.horman@...igine.com>, <aleksander.lobakin@...el.com>
Subject: Re: [PATCH net-next v2 1/3] net: add check for current MAC address
 in dev_set_mac_address

On Tue, Jun 13, 2023 at 02:24:18PM +0200, Piotr Gardocki wrote:
> In some cases it is possible for kernel to come with request
> to change primary MAC address to the address that is already
> set on the given interface.
> 
> This patch adds proper check to return fast from the function
> in these cases.

Please use imperative mood here - "add proper check..."

> 
> 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>

I'll let Kuba ack it.

> ---
>  net/core/dev.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/core/dev.c b/net/core/dev.c
> index c2456b3667fe..8f1c49ab17df 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -8754,6 +8754,8 @@ int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
>  		return -EINVAL;
>  	if (!netif_device_present(dev))
>  		return -ENODEV;
> +	if (!memcmp(dev->dev_addr, sa->sa_data, dev->addr_len))
> +		return 0;
>  	err = dev_pre_changeaddr_notify(dev, sa->sa_data, extack);
>  	if (err)
>  		return err;
> -- 
> 2.34.1
>