[PATCH net v2 1/1] net: stmmac: Prevent DSA tags from breaking COE on stmmac

[Florian Fainelli]

On 1/2/24 08:27, 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 at vger.kernel.org
> Reported-by: Richard Tresidder <rtresidd at electromag.com.au>
> Closes: https://lore.kernel.org/netdev/e5c6c75f-2dfa-4e50-a1fb-6bf4cdb617c2@electromag.com.au/
> Reported-by: Romain Gantois <romain.gantois at bootlin.com>
> Closes: https://lore.kernel.org/netdev/c57283ed-6b9b-b0e6-ee12-5655c1c54495@bootlin.com/

Fairly sure those should be Link: and Closes: should be used for bug 
tracker entries.

> Signed-off-by: Romain Gantois <romain.gantois at bootlin.com>
> ---
>   .../net/ethernet/stmicro/stmmac/stmmac_main.c | 21 ++++++++++++++++---
>   1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 37e64283f910..bb2ae6b32b2f 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -4371,6 +4371,17 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
>   	return NETDEV_TX_OK;
>   }
>   
> +/* Check if ethertype will trigger IP
> + * header checks/COE in hardware
> + */
> +static inline bool stmmac_has_ip_ethertype(struct sk_buff *skb)
> +{
> +	__be16 proto = eth_header_parse_protocol(skb);
> +
> +	return (proto == htons(ETH_P_IP)) || (proto == htons(ETH_P_IPV6)) ||
> +		(proto == htons(ETH_P_8021Q));

Do you need to include ETH_P_8021AD in that list as well or is not 
stmmac capable of checksuming beyond a single VLAN tag?

Thanks!
-- 
Florian