From: Wathsala Vithanage <wathsala.vithanage@arm.com>
To: Stephen Hemminger <stephen@networkplumber.org>,
Konstantin Ananyev <konstantin.ananyev@huawei.com>
Cc: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
Tyler Retzlaff <roretzla@linux.microsoft.com>,
"dev@dpdk.org" <dev@dpdk.org>,
Ola Liljedahl <ola.liljedahl@arm.com>,
"vattunuru@marvell.com" <vattunuru@marvell.com>
Subject: Re: [PATCH 1/1] eal: correct memory ordering in MCS lock
Date: Mon, 3 Nov 2025 13:13:37 -0600 [thread overview]
Message-ID: <455ee0d1-0393-4d8c-87b6-fa038b5ac303@arm.com> (raw)
In-Reply-To: <20251103104803.30464227@phoenix>
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On 11/3/25 12:48, Stephen Hemminger wrote:
> On Mon, 3 Nov 2025 18:06:05 +0000
> Konstantin Ananyev<konstantin.ananyev@huawei.com> wrote:
>
>>> On 11/3/25 11:07, Stephen Hemminger wrote:
>>>> On Mon, 3 Nov 2025 09:12:39 -0600
>>>> Wathsala Vithanage<wathsala.vithanage@arm.com> wrote:
>>>>
>>>>> MCS lock is broken, it's just a matter of time it will run into a deadlock.
>>>>>
>>>>> drivers/dma/cnxk is a user of MCS lock.
>>>> I am surprised that a driver would use mcslock.
>>>> MCSlock is targeted at case of large number of CPU's with lots of contention.
>>>> It will likely be slower than spinlock or ticketlock for the use case of driver.
>>> It appears in |drivers/dma/cnxk/cnxk_dmadev_fp.c|, perhaps the
>>> maintainer can clarify.
>>>
>> If MCS lock is really broken, it needs to be fixed anyway.
>> It might be used by other third-party libs/apps that do use on DPDK.
> 100% agree it must be fixed.
> It would be good to have test or static analysis tool that could validate all the lock types.
Looked at seqlock; it seems correct.
Herd7 has been useful, but it's not a static analysis tool. It requires
identifying a trouble
spot manually and then writing a litmus test to test the hypothesis.
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next prev parent reply other threads:[~2025-11-03 19:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-23 18:47 Wathsala Vithanage
2025-11-03 15:12 ` Wathsala Vithanage
2025-11-03 17:07 ` Stephen Hemminger
2025-11-03 17:30 ` Wathsala Vithanage
2025-11-03 18:06 ` Konstantin Ananyev
2025-11-03 18:47 ` Wathsala Vithanage
2025-11-03 18:48 ` Stephen Hemminger
2025-11-03 19:13 ` Wathsala Vithanage [this message]
2025-11-04 8:18 ` Konstantin Ananyev
2025-11-03 23:48 ` Stephen Hemminger
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