kthread Working

[Rajat Sharma]

On Mon, Sep 12, 2011 at 3:47 PM, Gaurav Mahajan
<gauravmahajan2007 at gmail.com> wrote:
> Hi,
>
> I have a douby regarding  kthread working.
>
> How can we check that a kthread is working or exited.
> It  may exit beacuse of call to do_exit in threadfn or callling kthread_stop
> function on task_struct (correct me if i am weong).
>
> I want to check that if kthread has finished its work or not.
> If not then what should I call so that kthread gets killed.
> If it is finshhed then which function I should call so that as to free
> kthread resources.
>
> Regards,
> Gaurav Mahajan.
>
>
>
>
>
>
>
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kthread_stop function should itself block untill thread gets killed.
However if thread is already killed, its task_struct won't be valid.
If its your thread, it should be fairly possible for you keep keep
single exit point, i.e. notify this thread to stop using
'kthread_stop'.

However if you are upto hacking some kernel thread, kthread_stop() may
not work on already exited task, as there won't be any way to identify
a killed thread. Probably you should avoid such design choices.

-Rajat