Messages in this thread | | | Date | Wed, 16 Aug 2023 22:40:20 +0200 | From | Sabrina Dubroca <> | Subject | Re: [RFC net-next v1 4/5] net: macsec: introduce mdo_insert_tx_tag |
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2023-08-11, 18:32:48 +0300, Radu Pirea (NXP OSS) wrote: > Offloading MACsec in PHYs requires inserting the SecTAG and the ICV in > the ethernet frame. This operation will increase the frame size with 32 > bytes.
"up to 32 bytes"?
The SecTAG and ICV can both be shorter, at least with the software implementation.
[...] > +static struct sk_buff *insert_tx_tag(struct sk_buff *skb, > + struct net_device *dev) > +{ [...] > + > + ctx.secy = &macsec->secy; > + ctx.skb = skb;
I think it would be a bit more readable to just pass the skb to ->mdo_insert_tx_tag instead of adding it to the context.
> + > + err = ops->mdo_insert_tx_tag(&ctx); > + if (err) > + goto cleanup;
[...] > @@ -3403,6 +3470,13 @@ static netdev_tx_t macsec_start_xmit(struct sk_buff *skb, > skb_dst_drop(skb); > dst_hold(&md_dst->dst); > skb_dst_set(skb, &md_dst->dst); > + > + skb = insert_tx_tag(skb, dev); > + if (IS_ERR(skb)) { > + dev->stats.tx_dropped++;
That should probably use DEV_STATS_INC (see commit 32d0a49d36a2 ("macsec: use DEV_STATS_INC()")).
> + return NETDEV_TX_OK; > + } > + > skb->dev = macsec->real_dev; > return dev_queue_xmit(skb); > } > @@ -4137,6 +4211,11 @@ static int macsec_newlink(struct net *net, struct net_device *dev, > if (err) > goto del_dev; > } > + > + dev->needed_headroom -= MACSEC_NEEDED_HEADROOM; > + dev->needed_headroom += ops->needed_headroom; > + dev->needed_tailroom -= MACSEC_NEEDED_TAILROOM; > + dev->needed_tailroom += ops->needed_tailroom;
If the driver doesn't set ops->needed_headroom, we'll subtract MACSEC_NEEDED_HEADROOM and not add anything back. Is that correct for all existing drivers? (and same for tailroom)
You set needed_tailroom to 0 in your driver, but the commit message for this patch says that the HW needs space for the ICV. I'm a bit puzzled by this, especially since MACSEC_NEEDED_TAILROOM already reserves space for the ICV.
Also, since this is pattern repeated twice more (with a sign change) in macsec_update_offload, we could probably stuff this into a helper (either modifying dev->needed_headroom directly, or returning the value to add/subtract).
> } >
[...] > @@ -302,6 +303,10 @@ struct macsec_ops { > int (*mdo_get_tx_sa_stats)(struct macsec_context *ctx); > int (*mdo_get_rx_sc_stats)(struct macsec_context *ctx); > int (*mdo_get_rx_sa_stats)(struct macsec_context *ctx); > + /* Offload tag */ > + int (*mdo_insert_tx_tag)(struct macsec_context *ctx); > + int needed_headroom; > + int needed_tailroom;
unsigned?
> };
-- Sabrina
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