[PATCH net-next 03/10] net: stmmac: move TSO VLAN tag insertion to core code

[Russell King (Oracle)]

stmmac_tso_xmit() checks whether the skbuff is trying to offload
vlan tag insertion to hardware, which from the comment in the code
appears to be buggy when the TSO feature is used.

Rather than stmmac_tso_xmit() inserting the VLAN tag, handle this
in stmmac_features_check() which will then use core net code to
handle this. See net/core/dev.c::validate_xmit_skb()

Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 21 +++++++------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index e21ca1c70c6d..ed3e9515cf25 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4419,19 +4419,6 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 	u8 proto_hdr_len, hdr;
 	dma_addr_t des;
 
-	/* Always insert VLAN tag to SKB payload for TSO frames.
-	 *
-	 * Never insert VLAN tag by HW, since segments split by
-	 * TSO engine will be un-tagged by mistake.
-	 */
-	if (skb_vlan_tag_present(skb)) {
-		skb = __vlan_hwaccel_push_inside(skb);
-		if (unlikely(!skb)) {
-			priv->xstats.tx_dropped++;
-			return NETDEV_TX_OK;
-		}
-	}
-
 	nfrags = skb_shinfo(skb)->nr_frags;
 	queue = skb_get_queue_mapping(skb);
 
@@ -4932,6 +4919,14 @@ static netdev_features_t stmmac_features_check(struct sk_buff *skb,
 	features = vlan_features_check(skb, features);
 
 	if (skb_is_gso(skb)) {
+		/* Always insert VLAN tag to SKB payload for TSO frames.
+		 *
+		 * Never insert VLAN tag by HW, since segments split by
+		 * TSO engine will be un-tagged by mistake.
+		 */
+		features &= ~(NETIF_F_HW_VLAN_STAG_TX |
+			      NETIF_F_HW_VLAN_CTAG_TX);
+
 		/* STM32MP25xx (dwmac v5.3) states "Do not enable time-based
 		 * scheduling for channels on which the TSO feature is
 		 * enabled." If we have a skb for a channel which has TBS
-- 
2.47.3