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

From: Florian Fainelli <f.fainelli@gmail.com>
To: Romain Gantois <romain.gantois@bootlin.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Maxime Chevallier <maxime.chevallier@bootlin.com>,
	Sylvain Girard <sylvain.girard@se.com>,
	Vladimir Oltean <olteanv@gmail.com>, Andrew Lunn <andrew@lunn.ch>,
	Pascal EBERHARD <pascal.eberhard@se.com>,
	Richard Tresidder <rtresidd@electromag.com.au>,
	Linus Walleij <linus.walleij@linaro.org>,
	netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org
Subject: Re: [PATCH net v2 1/1] net: stmmac: Prevent DSA tags from breaking COE on stmmac
Date: Tue, 2 Jan 2024 12:26:36 -0800	[thread overview]
Message-ID: <e2250240-db19-4cb6-93ca-2384a382cdd5@gmail.com> (raw)
In-Reply-To: <20240102162718.268271-2-romain.gantois@bootlin.com>

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@vger.kernel.org
> Reported-by: Richard Tresidder <rtresidd@electromag.com.au>
> Closes: https://lore.kernel.org/netdev/e5c6c75f-2dfa-4e50-a1fb-6bf4cdb617c2@electromag.com.au/
> Reported-by: Romain Gantois <romain.gantois@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@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

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