Re: [PATCH] dmaengine: dmatest: fix timeout caused by kthread_stop

[Jie Hai]

Hi, Vinod Koul,

Stop an ongoing test by
"echo 0 > /sys/module/dmatest/parameters/run".
If the current code is executed inside the while loop
"while (!(kthread_should_stop() ||
 (params->iterations &&
 total_tests >= params->iterations)))"
and before the call of "wait_event_freezable_timeout",
the "wait_event_freezable_timeout" will be interrupted
and result in  "time out" for the test even if the test
is not completed.



Operations to the problem is as follows,
and the failures are probabilistic:

modprobe hisi_dma
modprobe dmatest

echo 0 > /sys/module/dmatest/parameters/iterations
echo "dma0chan0" > /sys/module/dmatest/parameters/channel
echo "dma0chan1" > /sys/module/dmatest/parameters/channel
echo "dma0chan2" > /sys/module/dmatest/parameters/channel
echo 1 > /sys/module/dmatest/parameters/run
echo 0 > /sys/module/dmatest/parameters/run

dmesg:

[52575.636992] dmatest: Added 1 threads using dma0chan0
[52575.637555] dmatest: Added 1 threads using dma0chan1
[52575.638044] dmatest: Added 1 threads using dma0chan2
[52581.020355] dmatest: Started 1 threads using dma0chan0
[52581.020585] dmatest: Started 1 threads using dma0chan1
[52581.020814] dmatest: Started 1 threads using dma0chan2
[52587.705782] dmatest: dma0chan0-copy0: result #57691: 'test timed out' 
with src_off=0xfe6 dst_off=0x89 len=0x1d9a (0)
[52587.706527] dmatest: dma0chan0-copy0: summary 57691 tests, 1 failures 
51179.98 iops 411323 KB/s (0)
[52587.707028] dmatest: dma0chan1-copy0: result #63178: 'test timed out' 
with src_off=0xdf dst_off=0x6ab len=0x389e (0)
[52587.707767] dmatest: dma0chan1-copy0: summary 63178 tests, 1 failures 
62851.60 iops 503835 KB/s (0)
[52587.708376] dmatest: dma0chan2-copy0: result #60527: 'test timed out' 
with src_off=0x10e dst_off=0x58 len=0x3ea4 (0)
[52587.708951] dmatest: dma0chan2-copy0: summary 60527 tests, 1 failures 
52403.78 iops 420014 KB/s (0)


On 2024/4/18 1:18, Vinod Koul wrote:
> On 20-07-23, 19:41, Jie Hai wrote:
> > The change introduced by commit a7c01fa93aeb ("signal: break
> > out of wait loops on kthread_stop()") causes dmatest aborts
> > any ongoing tests and possible failure on the tests. This patch
>
> Have you see this failure? Any log of that..
>
> > use wait_event_timeout instead of wait_event_freezable_timeout
> > to avoid interrupting ongoing tests by signal brought by
> > kthread_stop().
> >
> > Signed-off-by: Jie Hai <haijie1@xxxxxxxxxx>
> > ---
> >   drivers/dma/dmatest.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
> > index ffe621695e47..c06b8b16645a 100644
> > --- a/drivers/dma/dmatest.c
> > +++ b/drivers/dma/dmatest.c
> > @@ -827,7 +827,7 @@ static int dmatest_func(void *data)
> >   		} else {
> >   			dma_async_issue_pending(chan);
> >   
> > -			wait_event_freezable_timeout(thread->done_wait,
> > +			ret = wait_event_timeout(thread->done_wait,
> >   					done->done,
> >   					msecs_to_jiffies(params->timeout));
> >   
> > --
> > 2.33.0