diff mbox series

[5.6,71/73] dmaengine: dmatest: Fix process hang when reading wait parameter

Message ID 20200504165510.510085799@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman May 4, 2020, 5:58 p.m. UTC 
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

commit aa72f1d20ee973d68f26d46fce5e1cf6f9b7e1ca upstream.

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 6138f967bccc

  ("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: 6138f967bccc ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dma/dmatest.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -240,7 +240,7 @@  static bool is_threaded_test_run(struct
 		struct dmatest_thread *thread;
 
 		list_for_each_entry(thread, &dtc->threads, node) {
-			if (!thread->done)
+			if (!thread->done && !thread->pending)
 				return true;
 		}
 	}