Patch "dmaengine: dmatest: Fix iteration non-stop logic" has been added to the 5.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    dmaengine: dmatest: Fix iteration non-stop logic

to the 5.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dmaengine-dmatest-fix-iteration-non-stop-logic.patch
and it can be found in the queue-5.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 55abd5d56296b08bff3d1c5580a207e4089a79ca
Author: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Date:   Fri Apr 24 19:11:42 2020 +0300

    dmaengine: dmatest: Fix iteration non-stop logic
    
    commit b9f960201249f20deea586b4ec814669b4c6b1c0 upstream.
    
    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>
    Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
    Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20200424161147.16895-1-andriy.shevchenko@xxxxxxxxxxxxxxx
    Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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;