net: hns3: pad the short tunnel frame before sending to hardware

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

----------------------------

The hardware can not handle short tunnel frames below or equal
to 64 bytes, and will cause vlan tag missing problem.

This patch pads packet size to 65 bytes for tunnel frames to
fix this bug.
Signed-off-by: NYonglong Liu <liuyonglong@huawei.com>
Reviewed-by: NJunxin Chen <chenjunxin1@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

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

@@ -61,6 +61,7 @@ MODULE_PARM_DESC(debug, " Network interface message level setting");
 #define HNS3_OUTER_VLAN_TAG	2
 
 #define HNS3_MIN_TX_LEN		33U
+#define HNS3_MIN_TUN_PKT_LEN	65U
 
 /* hns3_pci_tbl - PCI Device ID Table
  *
@@ -898,8 +899,13 @@ static int hns3_set_l2l3l4(struct sk_buff *skb, u8 ol4_proto,
 			       l4.tcp->doff);
 		break;
 	case IPPROTO_UDP:
-		if (hns3_tunnel_csum_bug(skb))
+		if (hns3_tunnel_csum_bug(skb)) {
+			int ret = skb_put_padto(skb, HNS3_MIN_TUN_PKT_LEN);
+			if (ret)
+				return ret;
+
 			return skb_checksum_help(skb);
+		}
 
 		hns3_set_field(*type_cs_vlan_tso, HNS3_TXD_L4CS_B, 1);
 		hns3_set_field(*type_cs_vlan_tso, HNS3_TXD_L4T_S,