[PATCH net] net: stmmac: keep gso_enabled_types in sync with netdev features

[Lorenzo Bianconi]

stmmac_set_gso_types() derives priv->gso_enabled_types all-or-nothing
from NETIF_F_TSO, but stmmac_set_gso_features() advertises NETIF_F_TSO,
NETIF_F_TSO6 and (on GMAC4) NETIF_F_GSO_UDP_L4 as independently
toggleable features. Since netdev_fix_features() only ties TSO6 to the
checksum features, disabling TSO (ethtool -K ethX tx-tcp-segmentation
off) leaves TSO6 enabled in dev->features while gso_enabled_types
becomes 0.

For a TCPv6 GSO skb the stack then keeps the frame unsegmented
(NETIF_F_TSO6 is still set), stmmac_features_check() does not clear the
GSO mask, and the stmmac_xmit() gate (gso_type & gso_enabled_types) is
false, so the multi-MSS skb is transmitted through the ordinary
descriptor path as a single oversized frame.

Derive each GSO type from its own feature bit instead, so the mask stays
in sync with dev->features and TCPv6 (or UDP L4 on GMAC4) segmentation
keeps working when only TSO is disabled.

Fixes: 2e4082e4b739 ("net: stmmac: simplify GSO/TSO test in stmmac_xmit()")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi at oss.qualcomm.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 24 ++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index a71f0df26378..3d3042afcdf4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4371,16 +4371,18 @@ static void stmmac_flush_tx_descriptors(struct stmmac_priv *priv, int queue)
 	stmmac_set_queue_tx_tail_ptr(priv, tx_q, queue, tx_q->cur_tx);
 }
 
-static void stmmac_set_gso_types(struct stmmac_priv *priv, bool tso)
+static void stmmac_set_gso_types(struct stmmac_priv *priv,
+				 netdev_features_t features)
 {
-	if (!tso) {
-		priv->gso_enabled_types = 0;
-	} else {
-		/* Manage oversized TCP frames for GMAC4 device */
-		priv->gso_enabled_types = SKB_GSO_TCPV4 | SKB_GSO_TCPV6;
-		if (priv->plat->core_type == DWMAC_CORE_GMAC4)
-			priv->gso_enabled_types |= SKB_GSO_UDP_L4;
-	}
+	priv->gso_enabled_types = 0;
+
+	if (features & NETIF_F_TSO)
+		priv->gso_enabled_types |= SKB_GSO_TCPV4;
+	if (features & NETIF_F_TSO6)
+		priv->gso_enabled_types |= SKB_GSO_TCPV6;
+	/* Manage oversized UDP frames for GMAC4 devices */
+	if (features & NETIF_F_GSO_UDP_L4)
+		priv->gso_enabled_types |= SKB_GSO_UDP_L4;
 }
 
 static void stmmac_set_gso_features(struct net_device *ndev)
@@ -4416,7 +4418,7 @@ static void stmmac_set_gso_features(struct net_device *ndev)
 	if (priv->plat->core_type == DWMAC_CORE_GMAC4)
 		ndev->hw_features |= NETIF_F_GSO_UDP_L4;
 
-	stmmac_set_gso_types(priv, true);
+	stmmac_set_gso_types(priv, ndev->hw_features);
 
 	dev_info(priv->device, "TSO feature enabled\n");
 }
@@ -6198,7 +6200,7 @@ static int stmmac_set_features(struct net_device *netdev,
 			stmmac_enable_sph(priv, priv->ioaddr, sph_en, chan);
 	}
 
-	stmmac_set_gso_types(priv, features & NETIF_F_TSO);
+	stmmac_set_gso_types(priv, features);
 
 	if (features & NETIF_F_HW_VLAN_CTAG_RX)
 		priv->hw->hw_vlan_en = true;

---
base-commit: dd057113ac7ba5bdd2aed3d9405305911152f911
change-id: 20260808-stmmac-fix-tso6-features-7fdc5e9448e2

Best regards,
-- 
Lorenzo Bianconi <lorenzo.bianconi at oss.qualcomm.com>