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Date:   Wed, 31 Jul 2019 13:03:28 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Peter Zijlstra <peterz@infradead.org>
cc:     LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Sebastian Siewior <bigeasy@linutronix.de>,
        Anna-Maria Gleixner <anna-maria@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        Julia Cartwright <julia@ni.com>
Subject: Re: [patch 7/7] posix-timers: Prepare for PREEMPT_RT
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On Wed, 31 Jul 2019, Peter Zijlstra wrote:

> On Wed, Jul 31, 2019 at 12:33:55AM +0200, Thomas Gleixner wrote:
> > +static struct k_itimer *timer_wait_running(struct k_itimer *timer,
> > +					   unsigned long *flags)
> > +{
> > +	const struct k_clock *kc = READ_ONCE(timer->kclock);
> > +	timer_t timer_id = READ_ONCE(timer->it_id);
> > +
> > +	/* Prevent kfree(timer) after dropping the lock */
> > +	rcu_read_lock();
> > +	unlock_timer(timer, *flags);
> > +
> > +	if (kc->timer_arm == common_hrtimer_arm)
> > +		hrtimer_cancel_wait_running(&timer->it.real.timer);
> > +	else if (kc == &alarm_clock)
> > +		hrtimer_cancel_wait_running(&timer->it.alarm.alarmtimer.timer);
> 
> 	else WARN();

Yup. Working on it ...