[PATCH V2 net] net: hns3: add dma_rmb() for rx description

[PATCH V2 net] net: hns3: add dma_rmb() for rx description

[Huazhong Tan]

From: Jian Shen <shenjian15@huawei.com>

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: e55970950556 ("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>
---
V1->V2: fixes comment from David Miller
---
 drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 3cb43b1..3b8598a 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/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;
 
-- 
2.7.4

Re: [PATCH V2 net] net: hns3: add dma_rmb() for rx description

[David Miller]

From: Huazhong Tan <tanhuazhong@huawei.com>
Date: Wed, 6 Mar 2019 11:26:37 +0800

> From: Jian Shen <shenjian15@huawei.com>
> 
> 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: e55970950556 ("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>
> ---
> V1->V2: fixes comment from David Miller

Applied and queued up for -stable, thank you.