netdev - Re: [PATCH net-next v7 1/2] macsec: add support for IFLA_MACSEC_OFFLOAD in macsec

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Date:   Mon, 9 Jan 2023 16:14:32 +0100
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     ehakim@...dia.com, atenart@...nel.org
Cc:     netdev@...r.kernel.org, raeds@...dia.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com
Subject: Re: [PATCH net-next v7 1/2] macsec: add support for
 IFLA_MACSEC_OFFLOAD in macsec_changelink

2023-01-09, 10:55:56 +0200, ehakim@...dia.com wrote:
> @@ -3840,6 +3835,12 @@ static int macsec_changelink(struct net_device *dev, struct nlattr *tb[],
>  	if (ret)
>  		goto cleanup;
>  
> +	if (data[IFLA_MACSEC_OFFLOAD]) {
> +		ret = macsec_update_offload(dev, nla_get_u8(data[IFLA_MACSEC_OFFLOAD]));
> +		if (ret)
> +			goto cleanup;
> +	}
> +
>  	/* If h/w offloading is available, propagate to the device */
>  	if (macsec_is_offloaded(macsec)) {
>  		const struct macsec_ops *ops;

There's a missing rollback of the offloading status in the (probably
quite unlikely) case that mdo_upd_secy fails, no? We can't fail
macsec_get_ops because macsec_update_offload would have failed
already, but I guess the driver could fail in mdo_upd_secy, and then
"goto cleanup" doesn't restore the offloading state.  Sorry I didn't
notice this earlier.

In case the IFLA_MACSEC_OFFLOAD attribute is provided and we're
enabling offload, we also end up calling the driver's mdo_add_secy,
and then immediately afterwards mdo_upd_secy, which probably doesn't
make much sense.

Maybe we could turn that into:

    if (data[IFLA_MACSEC_OFFLOAD]) {
        ... macsec_update_offload
    } else if (macsec_is_offloaded(macsec)) {
        /* If h/w offloading is available, propagate to the device */
        ... mdo_upd_secy
    }

Antoine, does that look reasonable to you?

-- 
Sabrina