[PATCH v3] net/ixgbe: add proper memory barriers for some Rx functions

[Konstantin Ananyev]

________________________________

Konstantin Ananyev
Mobile: +353-873459988
Email: konstantin.ananyev at huawei.com

From:zhoumin <zhoumin at loongson.cn>
To:Thomas Monjalon <thomas at monjalon.net>;Ruifeng Wang <Ruifeng.Wang at arm.com>;Zhang, Qi Z <qi.z.zhang at intel.com>
Cc:dev <dev at dpdk.org>;mb <mb at smartsharesystems.com>;konstantin.v.ananyev <konstantin.v.ananyev at yandex.ru>;Yang, Qiming <qiming.yang at intel.com>;Wu, Wenjun1 <wenjun1.wu at intel.com>;drc <drc at linux.vnet.ibm.com>;roretzla <roretzla at linux.microsoft.com>;stable <stable at dpdk.org>;maobibo <maobibo at loongson.cn>;nd <nd at arm.com>;David Marchand <david.marchand at redhat.com>;honnappa.nagarahalli <honnappa.nagarahalli at arm.com>;Tyler Retzlaff <roretzla at microsoft.com>;Konstantin Ananyev <konstantin.ananyev at huawei.com>
Date:2023-06-13 04:43:12
Subject:Re: [PATCH v3] net/ixgbe: add proper memory barriers for some Rx functions

Hi Thomas,

On Mon, June 12, 2023 at 8:44PM, Thomas Monjalon wrote:
> 12/06/2023 13:58, zhoumin:
>> On Mon, June 12, 2023 at 6:26PM, Thomas Monjalon wrote:
>>> 15/05/2023 04:10, Zhang, Qi Z:
>>>> From: Ruifeng Wang <Ruifeng.Wang at arm.com<mailto:Ruifeng.Wang at arm.com>>
>>>>> From: Min Zhou <zhoumin at loongson.cn<mailto:zhoumin at loongson.cn>>
>>>>>> ---
>>>>>> v3:
>>>>>> - Use rte_smp_rmb() as the proper memory barrier instead of rte_rmb()
>>>>>> ---
>>>>>> v2:
>>>>>> - Make the calling of rte_rmb() for all platforms
>>>>>> ---
>>> [...]
>>>>> Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com<mailto:ruifeng.wang at arm.com>>
>>>> Applied to dpdk-next-net-intel.
>>>>
>>>> Thanks
>>>> Qi
>>>>
>>> Why ignoring checkpatch?
>>> It is saying:
>>> "
>>> Warning in drivers/net/ixgbe/ixgbe_rxtx.c:
>>> Using rte_smp_[r/w]mb
>>> "
>>
>> I'm sorry. Should we never use rte_smp_[r/w]mb in the driver's code?
> No we should avoid.
> It has been decided to slowly replace such barriers.
> By the way, I think it is not enough documented.
> You can find an explanation in doc/guides/rel_notes/deprecation.rst
Thank your for providing the reference documents. I have read this file.
The explanation is clear and I get it.
> I think we should also add some notes to
> lib/eal/include/generic/rte_atomic.h
Yes, I do think so. The notes added at the definitions of
rte_smp_[r/w]mb are better.
> Tyler, Honnappa, Ruifeng, Konstantin, what do you think?
>
Yes, extra notes sounds like a reasonable thing to me.



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