Andy,
On 24/04/2020 at 18:11, Andy Shevchenko wrote:
Under some circumstances, i.e. when test is still running and about to
time out and user runs, for example,
grep -H . /sys/module/dmatest/parameters/*
the iterations parameter is not respected and test is going on and on until
user gives
echo 0 > /sys/module/dmatest/parameters/run
This is not what expected.
The history of this bug is interesting. I though that the commit
2d88ce76eb98 ("dmatest: add a 'wait' parameter")
is a culprit, but looking closer to the code I think it simple revealed the
broken logic from the day one, i.e. in the commit
0a2ff57d6fba ("dmaengine: dmatest: add a maximum number of test iterations")
which adds iterations parameter.
So, to the point, the conditional of checking the thread to be stopped being
first part of conjunction logic prevents to check iterations. Thus, we have to
always check both conditions to be able to stop after given iterations.
Since it wasn't visible before second commit appeared, I add a respective
Fixes tag.
Fixes: 2d88ce76eb98 ("dmatest: add a 'wait' parameter")
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
Yes, makes sense indeed:
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/dma/dmatest.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index a2cadfa2e6d78..4993e3e5c5b01 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -662,8 +662,8 @@ static int dmatest_func(void *data)
flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
ktime = ktime_get();
- while (!kthread_should_stop()
- && !(params->iterations && total_tests >= params->iterations)) {
+ while (!(kthread_should_stop() ||
+ (params->iterations && total_tests >= params->iterations))) {
struct dma_async_tx_descriptor *tx = NULL;
struct dmaengine_unmap_data *um;
dma_addr_t *dsts;
--
2.26.2
--
Nicolas Ferre
