From: Peter Hurley <peter@hurleysoftware.com>
To: Peter Zijlstra <peterz@infradead.org>,
Fengguang Wu <fengguang.wu@intel.com>
Cc: Jet Chen <jet.chen@intel.com>, Su Tao <tao.su@intel.com>,
Yuanhan Liu <yuanhan.liu@intel.com>, LKP <lkp@01.org>,
linux-kernel@vger.kernel.org,
Marcel Holtmann <marcel@holtmann.org>,
oleg@redhat.com
Subject: Re: [rfcomm_run] WARNING: CPU: 1 PID: 79 at kernel/sched/core.c:7156 __might_sleep()
Date: Thu, 02 Oct 2014 09:49:04 -0400 [thread overview]
Message-ID: <542D57D0.4030904@hurleysoftware.com> (raw)
In-Reply-To: <20141002124247.GD6324@worktop.programming.kicks-ass.net>
On 10/02/2014 08:42 AM, Peter Zijlstra wrote:
> On Thu, Oct 02, 2014 at 02:31:50PM +0200, Peter Zijlstra wrote:
>> @@ -2086,24 +2086,22 @@ static void rfcomm_kill_listener(void)
>>
>> static int rfcomm_run(void *unused)
>> {
>> + DEFINE_WAIT_FUNC(wait, woken_wake_function);
>> BT_DBG("");
>>
>> set_user_nice(current, -10);
>>
>> rfcomm_add_listener(BDADDR_ANY);
>>
>> - while (1) {
>> - set_current_state(TASK_INTERRUPTIBLE);
>> -
>> - if (kthread_should_stop())
>> - break;
>> + add_wait_queue(&rfcomm_wq, &wait);
>> + while (!kthread_should_stop()) {
>>
>> /* Process stuff */
>> rfcomm_process_sessions();
>>
>> - schedule();
>> + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
>> }
>> - __set_current_state(TASK_RUNNING);
>> + remove_wait_queue(&rfcomm_wq, &wait);
>>
>> rfcomm_kill_listener();
>>
>
> Hmm, I think there's a problem there. If someone were to do
> kthread_stop() before wait_woken() we'd not actually stop, because
> wait_woken() doesn't test KTHREAD_SHOULD_STOP before calling schedule().
Do you mean this situation?
CPU 0 | CPU 1
|
rfcomm_run() | kthread_stop()
... |
if (!test_bit(KTHREAD_SHOULD_STOP)) |
| set_bit(KTHREAD_SHOULD_STOP)
| wake_up_process()
wait_woken() | wait_for_completion()
set_current_state(INTERRUPTIBLE) |
if (!WQ_FLAG_WOKEN) |
schedule_timeout() |
|
Now both tasks are sleeping forever.
If yes, then wakeups from signals don't work either, right?
Regards,
Peter Hurley
next prev parent reply other threads:[~2014-10-02 13:49 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140930080228.GD9561@wfg-t540p.sh.intel.com>
2014-10-02 11:09 ` [rfcomm_run] WARNING: CPU: 1 PID: 79 at kernel/sched/core.c:7156 __might_sleep() Peter Zijlstra
2014-10-02 12:31 ` Peter Zijlstra
2014-10-02 12:38 ` Peter Hurley
2014-10-02 12:54 ` Peter Zijlstra
2014-10-02 13:05 ` Peter Hurley
2014-10-02 13:41 ` Peter Zijlstra
2014-10-02 12:42 ` Peter Zijlstra
2014-10-02 13:49 ` Peter Hurley [this message]
2014-10-02 13:52 ` Peter Zijlstra
2014-10-02 13:58 ` Peter Zijlstra
2014-10-02 14:16 ` Peter Hurley
2014-10-02 16:57 ` Peter Zijlstra
2014-10-02 19:18 ` Oleg Nesterov
2014-10-02 19:11 ` Oleg Nesterov
2014-10-02 19:49 ` Peter Hurley
2014-10-02 19:57 ` Peter Zijlstra
2014-10-02 20:10 ` Oleg Nesterov
2014-10-03 11:50 ` Peter Zijlstra
2014-10-03 17:56 ` Oleg Nesterov
2014-10-03 19:30 ` Oleg Nesterov
2014-10-04 8:42 ` Peter Zijlstra
2014-10-06 0:25 ` Oleg Nesterov
2014-10-06 9:19 ` Peter Zijlstra
2014-10-06 10:59 ` Paul E. McKenney
2014-10-06 16:21 ` Oleg Nesterov
2014-10-04 8:44 ` Peter Zijlstra
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