On Thu, 11 Jan 2024 15:58:51 +0100 Romain Gantois wrote:
> Some DSA tagging protocols change the EtherType field in the MAC header
> e.g. DSA_TAG_PROTO_(DSA/EDSA/BRCM/MTK/RTL4C_A/SJA1105). On TX these tagged
> frames are ignored by the checksum offload engine and IP header checker of
> some stmmac cores.
>
> On RX, the stmmac driver wrongly assumes that checksums have been computed
> for these tagged packets, and sets CHECKSUM_UNNECESSARY.
>
> Add an additional check in the stmmac TX and RX hotpaths so that COE is
> deactivated for packets with ethertypes that will not trigger the COE and
> IP header checks.
>
> Fixes: 6b2c6e4a938f ("net: stmmac: propagate feature flags to vlan")
> Cc: <stable@xxxxxxxxxxxxxxx>
nit: double space
> +/**
> + * stmmac_has_ip_ethertype() - Check if packet has IP ethertype
> + * @skb: socket buffer to check
> + *
> + * Check if a packet has an ethertype that will trigger the IP header checks
> + * and IP/TCP checksum engine of the stmmac core.
> + *
> + * Return: true if the ethertype can trigger the checksum engine, false otherwise
nit: please don't go over 80 chars unless there's a good reason.
we are old school and stick to checkpatch --max-line-length=80 in netdev
> if (csum_insertion &&
> - priv->plat->tx_queues_cfg[queue].coe_unsupported) {
> + (priv->plat->tx_queues_cfg[queue].coe_unsupported ||
> + !stmmac_has_ip_ethertype(skb))) {
nit: minor misalignment here, the '!' should be under 'p'
> if (unlikely(skb_checksum_help(skb)))
> goto dma_map_err;
> csum_insertion = !csum_insertion;
> @@ -4997,7 +5020,7 @@ static void stmmac_dispatch_skb_zc(struct stmmac_priv *priv, u32 queue,
> stmmac_rx_vlan(priv->dev, skb);
> skb->protocol = eth_type_trans(skb, priv->dev);
>
> - if (unlikely(!coe))
> + if (unlikely(!coe) || !stmmac_has_ip_ethertype(skb))
The lack of Rx side COE checking in this driver is kinda crazy.
Looking at enh_desc_coe_rdes0() it seems like RDES0_FRAME_TYPE
may be the indication we need here?
We can dig into it as a follow up but I'm guessing that sending
an IPv6 packet with extension headers will also make the device
skip checksumming, or a UDP packet with csum of 0?
