net: hns3: add existence checking before adding unicast mac address

It's not allowed to add two same unicast mac address entries to the
mac_vlan table. When modify the uc mac address of a VF device to the
same value with the PF device's, the PF device will lose its entry of
the mac_vlan table.

Lookup the mac address in the mac_vlan table, and add it if the entry
is inexistent.

Fixes: 46a3df9f ("net: hns3: Add HNS3 Acceleration Engine & Compatibility Layer Support")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c

@@ -4107,6 +4107,7 @@ int hclge_add_uc_addr_common(struct hclge_vport *vport,
 {
 	struct hclge_dev *hdev = vport->back;
 	struct hclge_mac_vlan_tbl_entry_cmd req;
+	struct hclge_desc desc;
 	u16 egress_port = 0;
 	int ret;
 
@@ -4140,7 +4141,21 @@ int hclge_add_uc_addr_common(struct hclge_vport *vport,
 
 	hclge_prepare_mac_addr(&req, addr);
 
-	ret = hclge_add_mac_vlan_tbl(vport, &req, NULL);
+	/* Lookup the mac address in the mac_vlan table, and add
+	 * it if the entry is inexistent. Repeated unicast entry
+	 * is not allowed in the mac vlan table.
+	 */
+	ret = hclge_lookup_mac_vlan_tbl(vport, &req, &desc, false);
+	if (ret == -ENOENT)
+		return hclge_add_mac_vlan_tbl(vport, &req, NULL);
+
+	/* check if we just hit the duplicate */
+	if (!ret)
+		ret = -EINVAL;
+
+	dev_err(&hdev->pdev->dev,
+		"PF failed to add unicast entry(%pM) in the MAC table\n",
+		addr);
 
 	return ret;
 }