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

From: Will Deacon
Date: Tue May 21 2013 - 11:12:27 EST

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:

[ 43.888424] dma0chan0-copy0: #1: transfer aborted with src_off=0x81f0 dst_off=0x9f4 len=0xdf29 (0)
[ 43.888526] dma0chan0-copy0: terminating after 1 tests, 0 failures (status 0)
[ 43.888635] dmatest: thread dma0chan0-copy0 exited with status 0

<reload module and start new tests>

[ 77.341405] dma0chan0-copy0: #1: errors with src_off=0x8e29 dst_off=0x11dc8 len=0x2b93 (370)
[ 77.341505] dma0chan0-copy0: terminating after 1 tests, 1 failures (status 0)

Note that the non-aborted transfers (I have 4 dma controllers) seem fine.

Looking at the results file doesn't show anything obvious, although I do
see some strange entries:

dstbuf not copied! [0xffffffff] Expected ff, got ff
dstbuf not copied! [0xffffffff] Expected ff, got ff
dstbuf not copied! [0xffffffff] Expected 00, got 00
dstbuf not copied! [0xffffffff] Expected 00, got 00
dstbuf not copied! [0xffffffff] Expected ff, got ff

The more alarming ones look like:

dstbuf not copied! [0x147e9] Expected d5, got 36
dstbuf not copied! [0x147ea] Expected d4, got 35
dstbuf not copied! [0x147eb] Expected d3, got 34
dstbuf not copied! [0x147ec] Expected d2, got 33
dstbuf not copied! [0x147ed] Expected d1, got 32
dstbuf not copied! [0x147ee] Expected d0, got 31

Of course, this could be a driver bug with the PL330 that is being exposed
by this aborting code.

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