Messages in this thread |  | | Subject | Re: [PATCH v1] kthread/smpboot: Serialize kthread parking against wakeup | From | "Kohli, Gaurav" <> | Date | Thu, 26 Apr 2018 21:23:25 +0530 |
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On 4/26/2018 2:27 PM, Peter Zijlstra wrote:
> On Thu, Apr 26, 2018 at 10:41:31AM +0200, Peter Zijlstra wrote: >> diff --git a/kernel/kthread.c b/kernel/kthread.c >> index cd50e99202b0..4b6503c6a029 100644 >> --- a/kernel/kthread.c >> +++ b/kernel/kthread.c >> @@ -177,12 +177,13 @@ void *kthread_probe_data(struct task_struct *task) >> >> static void __kthread_parkme(struct kthread *self) >> { >> - __set_current_state(TASK_PARKED); >> - while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) { >> + for (;;) { >> + __set_task_state(TASK_PARKED); > set_current_state(TASK_PARKED); > > of course..
Hi Peter,
Maybe i am missing something , but still that race can come as we don't put task_parked on special state.
Controller Hotplug
Loop
Task_Interruptible
Set SHOULD_PARK
wakeup -> Proceeds
Set Running
kthread_parkme
SET TASK_PARKED
schedule
Set TASK_RUNNING
Can you please correct ME, if I misunderstood this.
> >> + if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) >> + break; >> if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags)) >> complete(&self->parked); >> schedule(); >> - __set_current_state(TASK_PARKED); >> } >> clear_bit(KTHREAD_IS_PARKED, &self->flags); >> __set_current_state(TASK_RUNNING); >> >> -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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