Subject: [PATCH 05/26] net: hns3: pad the short frame before sending to the hardware

From: Yunsheng Lin <[email-masked]>
Date: Wed, 15 Jan 2020 10:46:45 +0800

[ Upstream commit 36c67349a1a1c88b9cf11d7ca7762ababdb38867 ]

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: 76ad4f0ee747 ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: Yunsheng Lin <[email-masked]>
Signed-off-by: Huazhong Tan <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 84d8816c8681..0c8d2269bc46 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/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
@@ -1329,6 +1331,10 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 	int ret;
 	int i;
 
+	/* 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);
 
-- 
2.21.1