Commit aa72f1d2 authored Apr 28, 2020 by Andy Shevchenko Committed by Vinod Koul Apr 28, 2020

dmaengine: dmatest: Fix process hang when reading 'wait' parameter



If we do

  % echo 1 > /sys/module/dmatest/parameters/run
  [  115.851124] dmatest: Could not start test, no channels configured

  % echo dma8chan7 > /sys/module/dmatest/parameters/channel
  [  127.563872] dmatest: Added 1 threads using dma8chan7

  % cat /sys/module/dmatest/parameters/wait
  ... !!! HANG !!! ...

The culprit is the commit 6138f967

  ("dmaengine: dmatest: Use fixed point div to calculate iops")

which makes threads not to run, but pending and being kicked off by writing
to the 'run' node. However, it forgot to consider 'wait' routine to avoid
above mentioned case.

In order to fix this, check for really running threads, i.e. with pending
and done flags unset.

It's pity the culprit commit hadn't updated documentation and tested all
possible scenarios.

Fixes: 6138f967 ("dmaengine: dmatest: Use fixed point div to calculate iops")
Cc: Seraj Alijan <seraj.alijan@sondrel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200428113518.70620-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>

parent b9f96020

drivers/dma/dmatest.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -240,7 +240,7 @@ static bool is_threaded_test_run(struct dmatest_info *info)
		struct dmatest_thread *thread;

		list_for_each_entry(thread, &dtc->threads, node) {
		if (!thread->done)
		if (!thread->done && !thread->pending)
		return true;
		}
		}

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