net: hns3: add dma_rmb() for rx description

HW can not guarantee complete write desc->rx.size, even though
HNS3_RXD_VLD_B has been set. Driver needs to add dma_rmb()
instruction to make sure desc->rx.size is always valid.

Fixes: e5597095 ("net: hns3: Add handling of GRO Pkts not fully RX'ed in NAPI poll")
Signed-off-by: Jian Shen <shenjian15@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

@@ -2472,6 +2472,8 @@ static int hns3_add_frag(struct hns3_enet_ring *ring, struct hns3_desc *desc,
 		desc = &ring->desc[ring->next_to_clean];
 		desc_cb = &ring->desc_cb[ring->next_to_clean];
 		bd_base_info = le32_to_cpu(desc->rx.bd_base_info);
+		/* make sure HW write desc complete */
+		dma_rmb();
 		if (!(bd_base_info & BIT(HNS3_RXD_VLD_B)))
 			return -ENXIO;