Subject: [PATCH v3 net] stmmac: Added support for 802.1ad S-TAG stripping

From: Elad Nachman <[email-masked]>
Date: Thu, 24 May 2018 19:56:16 +0300

stmmac reception handler calls stmmac_rx_vlan() to strip the vlan before calling napi_gro_receive().

The function assumes VLAN tagged frames are always tagged with 802.1Q protocol,
and assigns ETH_P_8021Q to the skb by hard-coding the parameter on call to __vlan_hwaccel_put_tag() .

This causes packets not to be passed to the VLAN slave if it was created with 802.1AD protocol
(ip link add link eth0 eth0.100 type vlan proto 802.1ad id 100).

This fix passes the protocol from the VLAN header into __vlan_hwaccel_put_tag()
instead of using the hard-coded value of ETH_P_8021Q.
NETIF_F_HW_VLAN_STAG_RX was added to the net device features to reflect this new support.

Signed-off-by: Elad Nachman <[email-masked]>

---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b65e2d1..2d2f37f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3293,17 +3293,19 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 
 static void stmmac_rx_vlan(struct net_device *dev, struct sk_buff *skb)
 {
-	struct ethhdr *ehdr;
+	struct vlan_ethhdr *veth;
 	u16 vlanid;
+	__be16 vlan_proto;
 
-	if ((dev->features & NETIF_F_HW_VLAN_CTAG_RX) ==
-	    NETIF_F_HW_VLAN_CTAG_RX &&
+	if ((dev->features & (NETIF_F_HW_VLAN_CTAG_RX|NETIF_F_HW_VLAN_STAG_RX)) ==
+	    (NETIF_F_HW_VLAN_CTAG_RX|NETIF_F_HW_VLAN_STAG_RX) &&
 	    !__vlan_get_tag(skb, &vlanid)) {
 		/* pop the vlan tag */
-		ehdr = (struct ethhdr *)skb->data;
-		memmove(skb->data + VLAN_HLEN, ehdr, ETH_ALEN * 2);
+		veth = (struct vlan_ethhdr *)skb->data;
+		vlan_proto = veth->h_vlan_proto;
+		memmove(skb->data + VLAN_HLEN, veth, ETH_ALEN * 2);
 		skb_pull(skb, VLAN_HLEN);
-		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlanid);
+		__vlan_hwaccel_put_tag(skb, vlan_proto, vlanid);
 	}
 }
 
@@ -4344,7 +4346,7 @@ int stmmac_dvr_probe(struct device *device,
 	ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
 #ifdef STMMAC_VLAN_TAG_USED
 	/* Both mac100 and gmac support receive VLAN tag detection */
-	ndev->features |= NETIF_F_HW_VLAN_CTAG_RX;
+	ndev->features |= (NETIF_F_HW_VLAN_CTAG_RX|NETIF_F_HW_VLAN_STAG_RX);
 #endif
 	priv->msg_enable = netif_msg_init(debug, default_msg_level);
 
-- 
2.7.4