Re: [PATCH] dmatest: abort transfers immediately when asked for

From: Andy Shevchenko
Date: Tue May 21 2013 - 13:24:28 EST

On Tue, May 21, 2013 at 6:11 PM, Will Deacon <will.deacon@xxxxxxx> wrote:
> Hi Andy,
> On Tue, May 21, 2013 at 01:33:17PM +0100, Andy Shevchenko wrote:
>> When thread is going to be stopped we have to unconditionally terminate all
>> ongoing transfers. Otherwise it would be possible that callback function will
>> be called on the next interrupt and will try to access to already freed
>> structures.
>> The patch introduces specific error message for this, though it doesn't
>> increase the counter of the failed tests.
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>> Reported-by: Will Deacon <will.deacon@xxxxxxx>
> Thanks for persevering with this! Although this patch definitely fixes the
> panic I was seeing, 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.

Have you ever see such behaviour on pre v3.10-rc1 kernels? (I mean
with old dmatest module)

With Best Regards,
Andy Shevchenko
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