Re: [PATCH] kernel/trace: Stop and wait for kthread on preempt irq module unload

[Xiao Yang]

On 2020/4/28 22:45, Steven Rostedt wrote:
diff --git a/kernel/trace/preemptirq_delay_test.c 
b/kernel/trace/preemptirq_delay_test.c
 index 1c28ca20e30b..6d9131ae7e8c 100644
 --- a/kernel/trace/preemptirq_delay_test.c
 +++ b/kernel/trace/preemptirq_delay_test.c
 @@ -113,15 +113,27 @@ static int preemptirq_delay_run(void *data)
        for (i = 0; i<  s; i++)
                (testfuncs[i])(i);
 +
 +      while (!kthread_should_stop()) {
 +              schedule();
 +              set_current_state(TASK_INTERRUPTIBLE);
 +      }
 +
 +      __set_current_state(TASK_RUNNING);
 +
        return 0;
   }

Hi Steven,

Thanks for your patch.

I also used the following steps to do test and didn't get any 
warning/panic after applying your patch.
---------------------------------
for i in $(seq 1 100); do modprobe preemptirq_delay_test test_mode=irq 
delay=500000; rmmod preemptirq_delay_test; done
for i in $(seq 1 100); do modprobe preemptirq_delay_test 
test_mode=preempt delay=500000; rmmod preemptirq_delay_test; done
---------------------------------

But I am not sure which fix(from you and Joel) is better.

Thanks,
Xiao Yang