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

From: Thomas Gleixner
Date: Mon Jun 08 2015 - 04:06:34 EST


On Mon, 8 Jun 2015, Oleg Nesterov wrote:

> 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;

That's gone in tip/timers/core.

> 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(...);

That's fixed as well.

Thanks,

tglx
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