net: hns3: fix for skb leak when doing selftest

If hns3_nic_net_xmit does not return NETDEV_TX_BUSY when doing
a loopback selftest, the skb is not freed in hns3_clean_tx_ring
or hns3_nic_net_xmit, which causes skb not freed problem.

This patch fixes it by freeing skb when hns3_nic_net_xmit does
not return NETDEV_TX_OK.

Fixes: c39c4d98 ("net: hns3: Add mac loopback selftest support in hns3 driver")
Signed-off-by: NYunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: NPeng Li <lipeng321@huawei.com>
Signed-off-by: NHuazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c

@@ -250,11 +250,13 @@ static int hns3_lp_run_test(struct net_device *ndev, enum hnae3_loop mode)
 
 		skb_get(skb);
 		tx_ret = hns3_nic_net_xmit(skb, ndev);
-		if (tx_ret == NETDEV_TX_OK)
+		if (tx_ret == NETDEV_TX_OK) {
 			good_cnt++;
-		else
+		} else {
+			kfree_skb(skb);
 			netdev_err(ndev, "hns3_lb_run_test xmit failed: %d\n",
 				   tx_ret);
+		}
 	}
 	if (good_cnt != HNS3_NIC_LB_TEST_PKT_NUM) {
 		ret_val = HNS3_NIC_LB_TEST_TX_CNT_ERR;