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    SubjectRe: [PATCH] dmatest: abort transfers immediately when asked for
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    On Wed, May 22, 2013 at 3:41 PM, Will Deacon <will.deacon@arm.com> wrote:
    > On Tue, May 21, 2013 at 06:24:15PM +0100, Andy Shevchenko wrote:
    >> On Tue, May 21, 2013 at 6:11 PM, Will Deacon <will.deacon@arm.com> wrote:
    >> > I now observe buffer verification failures in subsequent
    >> > test runs after an aborted run:
    >>
    >> I think the description to the commit adfa543e "dmatest: don't use
    >> set_freezable_with_signal()" may shed light on this.
    >>
    >> The background (if I got it correctly) is in race with done flag. So,
    >> we got a callback call from the DMA engine, but we don't know which
    >> transfer triggers it.
    >> I might be wrong. This is just an assumption.
    >
    > I've not managed to work out exactly what's going on, but it's certainly
    > something like that. In fact, I just managed to trigger a case where all but
    > one of the transfers is aborted, whilst the remaining one fails. Looking at
    > the code, I can't see how that situation comes about, since the threads are
    > protected with the info mutex and kthread_stop is synchronous.

    >> Have you ever see such behaviour on pre v3.10-rc1 kernels? (I mean
    >> with old dmatest module)
    >
    > No, dmatest from 3.9 is completely reliable in my experience.

    Yeah, I supposed that was a rhetorical question.

    So, have I understood correctly that if you revert the 77101ce5
    ("cancel thread ...")
    everything is working fine / as before?

    --
    With Best Regards,
    Andy Shevchenko


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