From: Eric Dumazet <eric.dumazet@gmail.com>
To: Dmitry Antipov <dmitry.antipov@linaro.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Module/kthread/printk question/problem
Date: Thu, 02 Feb 2012 08:45:01 +0100 [thread overview]
Message-ID: <1328168701.2902.14.camel@edumazet-laptop> (raw)
In-Reply-To: <4F2A296E.5080007@linaro.org>
Le jeudi 02 février 2012 à 10:13 +0400, Dmitry Antipov a écrit :
> On 02/01/2012 09:16 PM, Eric Dumazet wrote:
>
> >> I realize this, but there was a second part of the question: what's the
> >> better way to ensure that all test/X threads are really gone at some point of
> >> testmod_exit()?
> >>
> >
> > You could use kthread_stop()
> >
> > This way you can control all your kernel threads really exited before
> > module cleanup.
>
> Hm... if I try something like:
>
> static void __exit testmod_exit(void)
> {
> int i;
>
> wait_for_completion(&done);
> for (i = 0; i < nrthreads; i++)
> kthread_stop(threads[i]);
> kfree(threads);
> }
>
> typical result is:
> I suppose that __put_task_struct() was called for the thread when is 'partially dead'
> (because it's somewhere in do_exit() called by kthread() after returning from thread's
> function), but not 'dead enough' to finalize it with free_task().
>
> So, the question is still open.
>
Really you need to better understand how all this works.
Remove the wait_for_completion(), this brings nothing at all, as you
already discovered.
Then you need cooperation from worker threads : they must wait for
kthread_should_stop(), or else your kthread_stop(arg) pass an already
freed "arg" memory block.
Take the time to read kernel/kthread.c and function kthread_stop()
next prev parent reply other threads:[~2012-02-02 7:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 16:09 Module/kthread/printk question/problem Dmitry Antipov
2012-02-01 16:31 ` Eric Dumazet
2012-02-01 16:35 ` Dmitry Antipov
2012-02-01 17:16 ` Eric Dumazet
2012-02-02 6:13 ` Dmitry Antipov
2012-02-02 7:45 ` Eric Dumazet [this message]
2012-02-02 9:20 ` Dmitry Antipov
2012-02-02 9:15 ` Eric Dumazet
2012-02-02 9:22 ` Dmitry Antipov
2012-02-02 9:58 ` Eric Dumazet
2012-02-06 23:43 ` Rusty Russell
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