[PATCH net v3] net: stmmac: drop gso_enabled_types and rely on netdev features

The gso_enabled_types field is used by stmmac_xmit() to decide whether a
GSO skb should be passed to stmmac_tso_xmit(). It is updated in
stmmac_set_features() based solely on NETIF_F_TSO, so disabling IPv4
TSO while keeping IPv6 TSO (NETIF_F_TSO6) enabled zeroes the mask. As a
result IPv6 GSO frames, which the networking stack still generates since
NETIF_F_TSO6 is enabled, fall through to the non-TSO xmit path where
they are not handled.

The networking stack already manages the GSO logic: a GSO skb is only
delivered to the driver when the matching offload feature (NETIF_F_TSO,
NETIF_F_TSO6 or NETIF_F_GSO_UDP_L4) is enabled, otherwise the frame is
segmented in software before reaching ndo_start_xmit().
stmmac_features_check() also validates each GSO frame against the TSO
hardware constraints and falls back to software GSO when they are not met.

Drop the gso_enabled_types field and rely on skb_is_gso() in
stmmac_xmit() instead, which correctly routes IPv6 GSO frames to the TSO
path when NETIF_F_TSO is disabled. This also removes the data race
between stmmac_set_gso_types(), called from the feature-set path, and
the lockless read of gso_enabled_types in stmmac_xmit().

Fixes: 2e4082e4b739 ("net: stmmac: simplify GSO/TSO test in stmmac_xmit()")
Signed-off-by: Lorenzo Bianconi <redacted>
---
Changes in v3:
- Drop gso_enabled_types field and rely on the network stack to manage
  TSO/GSO logic.
- Link to v2: https://lore.kernel.org/r/20260812-stmmac-fix-tso6-features-v2-1-72c3b06eb8d4@oss.qualcomm.com (local)

Changes in v2:
- Fix possible race between stmmac_set_gso_types() and stmmac_xmit().
- Fix fixes tag.
- Link to v1: https://lore.kernel.org/r/20260808-stmmac-fix-tso6-features-v1-1-f82b17595052@oss.qualcomm.com (local)
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h      |  2 --
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 19 +------------------
 2 files changed, 1 insertion(+), 20 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 8ba8f03e1ce0..7582fca63741 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h

@@ -265,8 +265,6 @@ struct stmmac_priv {
 	u32 rx_coal_frames[MTL_MAX_RX_QUEUES];
 
 	int hwts_tx_en;
-	/* skb_shinfo(skb)->gso_type types that we handle */
-	unsigned int gso_enabled_types;
 	bool tx_path_in_lpi_mode;
 	bool sph_active;
 	bool sph_capable;

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b2b7d0242dd3..3a956c8b611b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -4375,18 +4375,6 @@ 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)
-{
-	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;
-	}
-}
-
 static void stmmac_set_gso_features(struct net_device *ndev)
 {
 	struct stmmac_priv *priv = netdev_priv(ndev);

@@ -4420,8 +4408,6 @@ 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);
-
 	dev_info(priv->device, "TSO feature enabled\n");
 }
 

@@ -4771,8 +4757,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (priv->tx_path_in_lpi_mode && priv->eee_sw_timer_en)
 		stmmac_stop_sw_lpi(priv);
 
-	if (skb_is_gso(skb) &&
-	    skb_shinfo(skb)->gso_type & priv->gso_enabled_types)
+	if (skb_is_gso(skb))
 		return stmmac_tso_xmit(skb, dev);
 
 	if (priv->est && priv->est->enable &&

@@ -6206,8 +6191,6 @@ 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);
-
 	if (features & NETIF_F_HW_VLAN_CTAG_RX)
 		priv->hw->hw_vlan_en = true;
 	else

---
base-commit: 7cbfb180945ce529608e4d4e24a6d483699fab1e
change-id: 20260808-stmmac-fix-tso6-features-7fdc5e9448e2

Best regards,
-- 
Lorenzo Bianconi [off-list ref]