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Re: [PATCH] kthread: Fix race condition between kthread_parkme() and kthread_unpark()

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On Thu, 28 Sep 2017, Junaid Shahid wrote:

> Hi Peter,
> 
> It looks like try_cmpxchg is not available on non-x86 archs, but other than
> that the version that you proposed looks good.
> 
> One thing that I am a bit curious about is that the original code, before
> either patch, had a test_and_set_bit for KTHREAD_IS_PARKED rather than just
> a set_bit. I can't think of any reason why that was needed, since it
> doesn't look like TASK_PARKED tasks are susceptible to spurious wakeups. Do
> you by any chance happen to know if there was any specific reason for it?

Everything is susceptible to spurious wakeups and has to deal with it.

Thanks,

	tglx

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Re: [PATCH] kthread: Fix race condition between kthread_parkme() and  kthread_unpark() Peter Zijlstra <peterz@infradead.org> - 2017-09-27 14:20 +0200
  Re: [PATCH] kthread: Fix race condition between kthread_parkme()  and kthread_unpark() Thomas Gleixner <tglx@linutronix.de> - 2017-09-29 10:10 +0200
    Re: [PATCH] kthread: Fix race condition between kthread_parkme() and  kthread_unpark() Peter Zijlstra <peterz@infradead.org> - 2017-09-29 10:30 +0200
      Re: [PATCH] kthread: Fix race condition between kthread_parkme() and kthread_unpark() Junaid Shahid <junaids@google.com> - 2017-09-29 23:00 +0200

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