net: hns3: add limit ets dwrr bandwidth cannot be 0

If ets dwrr bandwidth of tc is set to 0, the hardware will switch to SP
mode. In this case, this tc may occupy all the tx bandwidth if it has
huge traffic, so it violates the purpose of the user setting.

To fix this problem, limit the ets dwrr bandwidth must greater than 0.

Fixes: cacde27 ("net: hns3: Add hclge_dcb module for the support of DCB feature")
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -137,6 +137,15 @@ static int hclge_ets_sch_mode_validate(struct hclge_dev *hdev,
 				*changed = true;
 			break;
 		case IEEE_8021QAZ_TSA_ETS:
+			/* The hardware will switch to sp mode if bandwidth is
+			 * 0, so limit ets bandwidth must be greater than 0.
+			 */
+			if (!ets->tc_tx_bw[i]) {
+				dev_err(&hdev->pdev->dev,
+					"tc%u ets bw cannot be 0\n", i);
+				return -EINVAL;
+			}
+
 			if (hdev->tm_info.tc_info[i].tc_sch_mode !=
 				HCLGE_SCH_MODE_DWRR)
 				*changed = true;