net: hns3: Fix for rx vlan id handle to support Rev 0x21 hardware

In revision 0x20, we use vlan id != 0 to check whether a vlan tag
has been offloaded, so vlan id 0 is not supported.

In revision 0x21, rx buffer descriptor adds two bits to indicate
whether one or more vlan tags have been offloaded, so vlan id 0
is valid now.

This patch seperates the handle for vlan id 0, add vlan id 0 support
for revision 0x21.

Fixes: 5b5455a9ed5a ("net: hns3: Add STRP_TAGP field support for hardware revision 0x21")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3_enet.c

@@ -2200,18 +2200,18 @@ static void hns3_rx_skb(struct hns3_enet_ring *ring, struct sk_buff *skb)
 	napi_gro_receive(&ring->tqp_vector->napi, skb);
 }
 
-static u16 hns3_parse_vlan_tag(struct hns3_enet_ring *ring,
-			       struct hns3_desc *desc, u32 l234info)
+static bool hns3_parse_vlan_tag(struct hns3_enet_ring *ring,
+				struct hns3_desc *desc, u32 l234info,
+				u16 *vlan_tag)
 {
 	struct pci_dev *pdev = ring->tqp->handle->pdev;
-	u16 vlan_tag;
 
 	if (pdev->revision == 0x20) {
-		vlan_tag = le16_to_cpu(desc->rx.ot_vlan_tag);
-		if (!(vlan_tag & VLAN_VID_MASK))
-			vlan_tag = le16_to_cpu(desc->rx.vlan_tag);
+		*vlan_tag = le16_to_cpu(desc->rx.ot_vlan_tag);
+		if (!(*vlan_tag & VLAN_VID_MASK))
+			*vlan_tag = le16_to_cpu(desc->rx.vlan_tag);
 
-		return vlan_tag;
+		return (*vlan_tag != 0);
 	}
 
 #define HNS3_STRP_OUTER_VLAN	0x1
@@ -2220,17 +2220,14 @@ static u16 hns3_parse_vlan_tag(struct hns3_enet_ring *ring,
 	switch (hnae3_get_field(l234info, HNS3_RXD_STRP_TAGP_M,
 				HNS3_RXD_STRP_TAGP_S)) {
 	case HNS3_STRP_OUTER_VLAN:
-		vlan_tag = le16_to_cpu(desc->rx.ot_vlan_tag);
-		break;
+		*vlan_tag = le16_to_cpu(desc->rx.ot_vlan_tag);
+		return true;
 	case HNS3_STRP_INNER_VLAN:
-		vlan_tag = le16_to_cpu(desc->rx.vlan_tag);
-		break;
+		*vlan_tag = le16_to_cpu(desc->rx.vlan_tag);
+		return true;
 	default:
-		vlan_tag = 0;
-		break;
+		return false;
 	}
-
-	return vlan_tag;
 }
 
 static int hns3_handle_rx_bd(struct hns3_enet_ring *ring,
@@ -2332,8 +2329,7 @@ static int hns3_handle_rx_bd(struct hns3_enet_ring *ring,
 	if (netdev->features & NETIF_F_HW_VLAN_CTAG_RX) {
 		u16 vlan_tag;
 
-		vlan_tag = hns3_parse_vlan_tag(ring, desc, l234info);
-		if (vlan_tag & VLAN_VID_MASK)
+		if (hns3_parse_vlan_tag(ring, desc, l234info, &vlan_tag))
 			__vlan_hwaccel_put_tag(skb,
 					       htons(ETH_P_8021Q),
 					       vlan_tag);