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

[Steven Rostedt]

On Tue, 28 Apr 2020 18:19:05 +0800
Xiao Yang <yangx...@cn.fujitsu.com> wrote:

> Hi Joel,
> 
> Thanks for your quick fix.
> 
> Unfortunately, it fixes my original panic but introduces other
> issues(two wanings and one panic) on my arm64 vm, as below:
>

Does the following on top of Joel's patch fix it?

-- Steve

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;
 }
 
 static struct task_struct *preemptirq_start_test(void)
 {
+       struct task_struct *task;
        char task_name[50];
 
        snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
-       return kthread_run(preemptirq_delay_run, NULL, task_name);
+       task = kthread_run(preemptirq_delay_run, NULL, task_name);
+       if (IS_ERR(task))
+               return NULL;
+       return task;
 }