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

[Nathan Lynch]

Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx> writes:
> Nathan Lynch <nathan.lynch@xxxxxxx> writes:
>> Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx> writes:
>>> My understanding (and testing) is that wait_event_timeout() will block
>>> for the duration even in the face of interrupts, 'freezable' will not.
>>
>> They have different behaviors with respect to *signals* and the
>> wake_up() variant used, but not device interrupts.
>>
>
> Ah! That's something that I wasn't considering. That it could be
> something other than interrupts that were unblocking wait_event_*().

Well, I doubt it would be a signal in this case. Maybe you've
experienced timeouts?

>> 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.