Re: [PATCH net-next] macsec: no longer rely on RTNL in macsec_fill_info()

[Sabrina Dubroca <sd@queasysnail.net>]

2026-07-01, 09:43:41 +0000, Eric Dumazet wrote:
> Add READ_ONCE()/WRITE_ONCE() annotations on fields that can be
> changed concurrently in macsec_changelink() and macsec_update_offload():
> 
> - secy->key_len
> - secy->xpn

Those can't be changed, macsec_changelink() rejects
IFLA_MACSEC_CIPHER_SUITE (as well as IFLA_MACSEC_ICV_LEN and
IFLA_MACSEC_SCI) and key_len/xpn are fully linked to the cipher suite.

But I don't mind the extra READ/WRITE_ONCE if you don't want to
resend.

Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>

> - tx_sc->encoding_sa
> - tx_sc->encrypt
> - secy->protect_frames
> - tx_sc->send_sci
> - tx_sc->end_station
> - tx_sc->scb
> - secy->replay_protect
> - secy->validate_frames
> - secy->replay_window
> - macsec->offload
> 
> This allows macsec_fill_info() to run locklessly without RTNL.

And at some point, the whole datapath probably needs some READ_ONCE()
sprinkled for those fields, too.


> @@ -3928,13 +3929,14 @@ static int macsec_changelink_common(struct net_device *dev,
>  	}
>  
>  	if (data[IFLA_MACSEC_WINDOW]) {
> -		secy->replay_window = nla_get_u32(data[IFLA_MACSEC_WINDOW]);
> +		u32 replay_window = nla_get_u32(data[IFLA_MACSEC_WINDOW]);
>  
>  		/* IEEE 802.1AEbw-2013 10.7.8 - maximum replay window
>  		 * for XPN cipher suites */
>  		if (secy->xpn &&
> -		    secy->replay_window > MACSEC_XPN_MAX_REPLAY_WINDOW)
> +		    replay_window > MACSEC_XPN_MAX_REPLAY_WINDOW)

nit: no longer > 80 chars

-- 
Sabrina