[dpdk-dev] [PATCH 09/13] net/hns3: fix maximum frame size update after buffer alloc

[Lijun Ou]

From: Chengchang Tang <tangchengchang at huawei.com>

After MTU changed, the buffer used to store packets in HW should be
reallocated. And buffer size is allocated based on the maximum frame
size in the PF struct. However, the value of maximum frame size  is
not updated in time when MTU is changed. This would lead to a packet
loss for not enough buffer.

This patch update the maximum frame size before reallocating the HW
buffer. And a rollback operation is added to avoid the side effects
of buffer reallocation failures.

Fixes: 1f5ca0b460cd ("net/hns3: support some device operations")
Fixes: d51867db65c1 ("net/hns3: add initialization")
Cc: stable at dpdk.org

Signed-off-by: Chengchang Tang <tangchengchang at huawei.com>
Signed-off-by: Lijun Ou <oulijun at huawei.com>
---
 drivers/net/hns3/hns3_ethdev.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/net/hns3/hns3_ethdev.c b/drivers/net/hns3/hns3_ethdev.c
index b3fd331..21c3c59 100644
--- a/drivers/net/hns3/hns3_ethdev.c
+++ b/drivers/net/hns3/hns3_ethdev.c
@@ -2460,17 +2460,33 @@ hns3_set_mac_mtu(struct hns3_hw *hw, uint16_t new_mps)
 static int
 hns3_config_mtu(struct hns3_hw *hw, uint16_t mps)
 {
+	struct hns3_adapter *hns = HNS3_DEV_HW_TO_ADAPTER(hw);
+	uint16_t original_mps = hns->pf.mps;
+	int err;
 	int ret;
 
 	ret = hns3_set_mac_mtu(hw, mps);
 	if (ret) {
-		hns3_err(hw, "Failed to set mtu, ret = %d", ret);
+		hns3_err(hw, "failed to set mtu, ret = %d", ret);
 		return ret;
 	}
 
+	hns->pf.mps = mps;
 	ret = hns3_buffer_alloc(hw);
-	if (ret)
-		hns3_err(hw, "Failed to allocate buffer, ret = %d", ret);
+	if (ret) {
+		hns3_err(hw, "failed to allocate buffer, ret = %d", ret);
+		goto rollback;
+	}
+
+	return 0;
+
+rollback:
+	err = hns3_set_mac_mtu(hw, original_mps);
+	if (err) {
+		hns3_err(hw, "fail to rollback MTU, err = %d", err);
+		return ret;
+	}
+	hns->pf.mps = original_mps;
 
 	return ret;
 }
@@ -2505,7 +2521,7 @@ hns3_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 			 dev->data->port_id, mtu, ret);
 		return ret;
 	}
-	hns->pf.mps = (uint16_t)frame_size;
+
 	if (is_jumbo_frame)
 		dev->data->dev_conf.rxmode.offloads |=
 						DEV_RX_OFFLOAD_JUMBO_FRAME;
-- 
2.7.4