Re: [PATCH v2] dmaengine: dmatest: fix race between wait for thread and thread start

[claudiu beznea <claudiu.beznea@tuxon.dev>]

On 8/28/26 18:10, Cosmin Tanislav wrote:
> Each dmatest worker thread has a pending and a done flag which describe
> the thread's lifecycle.
> 
> pending is initialized to true when the thread is added to the threads
> list. pending is set to false once the thread is actually running. done
> is set to true once the thread has finished its testing.
> 
> When the wait module parameter is set to true, dmatest_init() waits for
> the !is_threaded_test_run() condition to become true.
> 
> If the worker thread is not started and running by the time
> dmatest_init() waits, the !is_threaded_test_run() condition will be true
> and the wait will stop early, before the worker thread is even started.
> dmatest_init() exits, defeating the whole purpose of the wait.
> 
> If then we try to remove the module, kthread_stop() will try to cleanup
> the worker threads, interrupting wait_event_freezable_timeout(), which
> will return -ERESTARTSYS, causing the "test timed out" message to be
> printed.
> 
> Clear the pending flag once we wake up the worker thread to avoid this
> race.
> 
> Fixes: d53513d5dc28 ("dmaengine: dmatest: Add support for multi channel testing")
> Signed-off-by: Cosmin Tanislav<cosmin-gabriel.tanislav.xa@renesas.com>

I've tested this on RZ/Five and RZ/V2L, on top of next-20261002. There are no 
more "test timed out" reported.

Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>