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

The hardware can not handle short frames below or equal to 32
bytes according to the hardware user manual, and it will trigger
a RAS error when the frame's length is below 33 bytes.

This patch pads the SKB when skb->len is below 33 bytes before
sending it to hardware.

Fixes: 76ad4f0e ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -54,6 +54,8 @@ MODULE_PARM_DESC(debug, " Network interface message level setting");
 #define HNS3_INNER_VLAN_TAG	1
 #define HNS3_OUTER_VLAN_TAG	2
 
+#define HNS3_MIN_TX_LEN		33U
+
 /* hns3_pci_tbl - PCI Device ID Table
  *
  * Last entry must be all 0s
@@ -1405,6 +1407,10 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 	int bd_num = 0;
 	int ret;
 
+	/* Hardware can only handle short frames above 32 bytes */
+	if (skb_put_padto(skb, HNS3_MIN_TX_LEN))
+		return NETDEV_TX_OK;
+
 	/* Prefetch the data used later */
 	prefetch(skb->data);