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Message-ID: <Y71QEvGlJXhsCGYP@hog> Date: Tue, 10 Jan 2023 12:46:26 +0100 From: Sabrina Dubroca <sd@...asysnail.net> To: Antoine Tenart <atenart@...nel.org> Cc: Emeel Hakim <ehakim@...dia.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, Raed Salem <raeds@...dia.com>, "davem@...emloft.net" <davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com> Subject: Re: [PATCH net-next v7 1/2] macsec: add support for IFLA_MACSEC_OFFLOAD in macsec_changelink 2023-01-10, 11:29:27 +0100, Antoine Tenart wrote: > Quoting Emeel Hakim (2023-01-10 10:05:36) > > > Quoting Sabrina Dubroca (2023-01-09 16:14:32) > > > > 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]) { > > > > > > If data[IFLA_MACSEC_OFFLOAD] is provided but doesn't change the offloading > > > state, then macsec_update_offload will return early and mdo_upd_secy won't be > > > called. > > > > > > > ... 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? > > > > > > But yes I agree we can improve the logic. Maybe something like: > > > > Ack , I can do the change > > > > > prev_offload = macsec->offload; > > > offload = data[IFLA_MACSEC_OFFLOAD]; > > > > > > if (prev_offload != offload) { > > > macsec_update_offload(...) > > > } else if (macsec_is_offloaded(macsec)) { > > > ... > > > prev_offload can be used to restore the offloading state on > > > failure here. > > > > why do we need to restore offloading state here in case of failure? > > we get to this case when prev_offload == offload. > > Right, not restoring. The general question is: what to do with > offloading on and an hw in an unknown state (upd failed). Right, but I don't think that's introduced by this patch. I don't want to block Emeel's patches because of an issue that was present before. Do we need a way to distinguish - update failed but the HW is still offloading the old state, just roll back - update failed, this macsec device can't be offloaded anymore (or at least not until $unclear_condition) and maybe some other variants (destroy and recreate the macsec device? reload the NIC driver?)? Would that help? Is that a useful distinction for admins and management software? -- Sabrina
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