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

[PATCH net] net: hns3: add 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 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>
---
 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 1bf7a5f..26d3bf4 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -2476,6 +2476,8 @@ 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 */
+		rmb();
 		if (!hnae3_get_bit(bd_base_info, HNS3_RXD_VLD_B))
 			return -ENXIO;
 
-- 
2.7.4

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

[David Miller]

From: Huazhong Tan <tanhuazhong@huawei.com>
Date: Sat, 2 Mar 2019 16:49:30 +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 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>

dma_rmb() is more appropriate here and more efficient.

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

[tanhuazhong]

On 2019/3/4 13:15, David Miller wrote:
> From: Huazhong Tan <tanhuazhong@huawei.com>
> Date: Sat, 2 Mar 2019 16:49:30 +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 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>
> 
> dma_rmb() is more appropriate here and more efficient.
> 

Thanks, will send V2  to fix it.

> .
>