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Re: [PATCH 08/14] hrtimer: Allow hrtimer::function() to free the timer

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On 06/08, Oleg Nesterov wrote:
>
> And I simply can not understand the complication in hrtimer_active(),
> please help!

Sorry for another off-topic email, but I don't even understand the
usage of hrtimer_active().

Say, do_nanosleep()

		hrtimer_start_expires(&t->timer, mode);
		if (!hrtimer_active(&t->timer))
			t->task = NULL;

why? Assuming that hrtimer_active() is correct, it can only return
false if t->task was already cleared by hrtimer_wakeup().


OTOH. perf_cpu_hrtimer_restart() does

	if (hrtimer_active(hr))
		return;

	if (!hrtimer_callback_running(hr))
		__hrtimer_start_range_ns(...);

why it can't simply do

	if (!hrtimer_active(hr)) // implies !hrtimer_callback_running()
		__hrtimer_start_range_ns(...);


Confused.

Oleg.

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Re: [PATCH 08/14] hrtimer: Allow hrtimer::function() to free the  timer Oleg Nesterov <oleg@redhat.com> - 2015-06-08 00:40 +0200
  Re: [PATCH 08/14] hrtimer: Allow hrtimer::function() to free the  timer Oleg Nesterov <oleg@redhat.com> - 2015-06-08 01:00 +0200
  Re: [PATCH 08/14] hrtimer: Allow hrtimer::function() to free the  timer Peter Zijlstra <peterz@infradead.org> - 2015-06-08 13:00 +0200
  Re: [PATCH 0/3] hrtimer: HRTIMER_STATE_ fixes Peter Zijlstra <peterz@infradead.org> - 2015-06-08 21:10 +0200
  Re: [PATCH 08/14] hrtimer: Allow hrtimer::function() to free the  timer Peter Zijlstra <peterz@infradead.org> - 2015-06-11 00:40 +0200

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