[PATCH net-next v1 1/1] net: mv643xx_eth: disable IP tx checksum with jumbo frames for Armada 310

[PATCH net-next v1 1/1] net: mv643xx_eth: disable IP tx checksum with jumbo frames for Armada 310

[Qingtao Cao]

The Ethernet controller found in Armada 310 doesn't support TCP/IP checksum
with frame sizes larger than its TX checksum offload limit

When the path MTU is larger than this limit, the skb_warn_bad_offload will
throw out a warning oops

Disable the TX checksum offload (NETIF_F_IP_CSUM) when the MTU is set to a
value larger than this limit, the NETIF_F_TSO will automatically be disabled
as a result and the IP stack will calculate jumbo frames' checksum instead.

Signed-off-by: Qingtao Cao <qingtao.cao@digi.com>
---
 drivers/net/ethernet/marvell/mv643xx_eth.c | 23 +++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
index 9e80899546d9..808877dd3549 100644
--- a/drivers/net/ethernet/marvell/mv643xx_eth.c
+++ b/drivers/net/ethernet/marvell/mv643xx_eth.c
@@ -2558,6 +2558,23 @@ static int mv643xx_eth_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	return ret;
 }
 
+static netdev_features_t mv643xx_eth_fix_features(struct net_device *dev,
+						  netdev_features_t features)
+{
+	struct mv643xx_eth_private *mp = netdev_priv(dev);
+
+	if (mp->shared->tx_csum_limit &&
+	    dev->mtu > mp->shared->tx_csum_limit) {
+		/* Kernel disables TSO when there is no TX checksum offload */
+		features &= ~NETIF_F_IP_CSUM;
+		netdev_info(dev,
+			    "Disable IP TX checksum and TSO offload for MTU > %dB\n",
+			    mp->shared->tx_csum_limit);
+	}
+
+	return features;
+}
+
 static int mv643xx_eth_change_mtu(struct net_device *dev, int new_mtu)
 {
 	struct mv643xx_eth_private *mp = netdev_priv(dev);
@@ -2566,8 +2583,10 @@ static int mv643xx_eth_change_mtu(struct net_device *dev, int new_mtu)
 	mv643xx_eth_recalc_skb_size(mp);
 	tx_set_rate(mp, 1000000000, 16777216);
 
-	if (!netif_running(dev))
+	if (!netif_running(dev)) {
+		netdev_update_features(dev);
 		return 0;
+	}
 
 	/*
 	 * Stop and then re-open the interface. This will allocate RX
@@ -2581,6 +2600,7 @@ static int mv643xx_eth_change_mtu(struct net_device *dev, int new_mtu)
 			   "fatal error on re-opening device after MTU change\n");
 	}
 
+	netdev_update_features(dev);
 	return 0;
 }
 
@@ -3079,6 +3099,7 @@ static const struct net_device_ops mv643xx_eth_netdev_ops = {
 	.ndo_set_mac_address	= mv643xx_eth_set_mac_address,
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_eth_ioctl		= mv643xx_eth_ioctl,
+	.ndo_fix_features       = mv643xx_eth_fix_features,
 	.ndo_change_mtu		= mv643xx_eth_change_mtu,
 	.ndo_set_features	= mv643xx_eth_set_features,
 	.ndo_tx_timeout		= mv643xx_eth_tx_timeout,
-- 
2.34.1

Re: [PATCH net-next v1 1/1] net: mv643xx_eth: disable IP tx checksum with jumbo frames for Armada 310

[Jakub Kicinski]

On Mon, 18 Nov 2024 10:45:09 +1000 Qingtao Cao wrote:
> The Ethernet controller found in Armada 310 doesn't support TCP/IP checksum
> with frame sizes larger than its TX checksum offload limit
> 
> When the path MTU is larger than this limit, the skb_warn_bad_offload will
> throw out a warning oops
> 
> Disable the TX checksum offload (NETIF_F_IP_CSUM) when the MTU is set to a
> value larger than this limit, the NETIF_F_TSO will automatically be disabled
> as a result and the IP stack will calculate jumbo frames' checksum instead.

I thought I suggested ndo_features_check, why are you using
fix_features?
-- 
pw-bot: cr