linux-kernel - Re: [PATCH v1] dmaengine: dmatest: Fix dmatest waiting less when interrupted

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Message-ID: <874iz58b6y.fsf@AUSNATLYNCH.amd.com>
Date: Thu, 3 Apr 2025 11:24:53 -0500
From: Nathan Lynch <nathan.lynch@....com>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>, Vinod Koul
	<vkoul@...nel.org>, <dmaengine@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <dave.jiang@...el.com>, <kristen.c.accardi@...el.com>, kernel test robot
	<oliver.sang@...el.com>
Subject: Re: [PATCH v1] dmaengine: dmatest: Fix dmatest waiting less when
 interrupted

Vinicius Costa Gomes <vinicius.gomes@...el.com> writes:
> Nathan Lynch <nathan.lynch@....com> writes:
>
>> Vinicius Costa Gomes <vinicius.gomes@...el.com> writes:
>>> Nathan Lynch <nathan.lynch@....com> writes:
>>>
>>>> Vinicius Costa Gomes <vinicius.gomes@...el.com> writes:
>>>>> Nathan Lynch <nathan.lynch@....com> writes:
>>>>>> dmatest_callback() employs wake_up_all(), which means this change
>>>>>> introduces no beneficial difference in the wakeup behavior. The dmatest
>>>>>> thread gets woken on receipt of the completion interrupt either way.
>>>>>>
>>>>>> And to reiterate, the change regresses the combination of dmatest and
>>>>>> the task freezer, which is a use case people have cared about,
>>>>>> apparently.
>>>>>>
>>>>>
>>>>> If this change in behavior causes a regression for others, glad to send
>>>>> a revert and find another solution.
>>>>
>>>> Thanks - yes it should be reverted or dropped IMO.
>>>
>>> Here's what I am thinking, I'll work on this a few days and see if I can
>>> find an alternative solution and send the revert together with the fix.
>>> If I can't find another solution in a few days, I'll propose the revert
>>> anyway.
>>
>> Just checking on this - I see this regression is in Linus's master
>> branch now.
>
> I have a series with the revert, a (hopefully better) fix for this
> issue, and a couple of others that I found along the way, that I should
> be able to propose soon.

Respectfully, I don't think that's how this should be handled. The
revert should be standalone, not part of a larger series subject to its
own cycle of review and revision.

I've written it up and submitted it myself.