Commit 902a9f9c authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
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tick: Mark tick related hrtimers to expiry in hard interrupt context 



The tick related hrtimers, which drive the scheduler tick and hrtimer based
broadcasting are required to expire in hard interrupt context for obvious
reasons.

Mark them so PREEMPT_RT kernels wont move them to soft interrupt expiry.

Make the horribly formatted RCU_NONIDLE bracket maze readable while at it.

No functional change, 

[ tglx: Split out from larger combo patch. Add changelog ]

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.459144407@linutronix.de
parent 2c0d278f

kernel/time/tick-broadcast-hrtimer.c

+9 −4
Original line number Diff line number Diff line
@@ -59,11 +59,16 @@ static int bc_set_next(ktime_t expires, struct clock_event_device *bc) 
	 * hrtimer_{start/cancel} functions call into tracing,

	 * calls to these functions must be bound within RCU_NONIDLE.

	 */

	RCU_NONIDLE({

	RCU_NONIDLE(

		{

			bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0;

			if (bc_moved)

			if (bc_moved) {

				hrtimer_start(&bctimer, expires,

					      HRTIMER_MODE_ABS_PINNED);});

					      HRTIMER_MODE_ABS_PINNED_HARD);

			}

		}

	);



	if (bc_moved) {

		/* Bind the "device" to the cpu */

		bc->bound_on = smp_processor_id();
@@ -104,7 +109,7 @@ static enum hrtimer_restart bc_handler(struct hrtimer *t) 


void tick_setup_hrtimer_broadcast(void)

{

	hrtimer_init(&bctimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);

	hrtimer_init(&bctimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);

	bctimer.function = bc_handler;

	clockevents_register_device(&ce_broadcast_hrtimer);

}

kernel/time/tick-sched.c

+9 −6
Original line number Diff line number Diff line
@@ -634,10 +634,12 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) 
	/* Forward the time to expire in the future */

	hrtimer_forward(&ts->sched_timer, now, tick_period);



	if (ts->nohz_mode == NOHZ_MODE_HIGHRES)

		hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED);

	else

	if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {

		hrtimer_start_expires(&ts->sched_timer,

				      HRTIMER_MODE_ABS_PINNED_HARD);

	} else {

		tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);

	}



	/*

	 * Reset to make sure next tick stop doesn't get fooled by past
@@ -802,7 +804,8 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) 
	}



	if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {

		hrtimer_start(&ts->sched_timer, tick, HRTIMER_MODE_ABS_PINNED);

		hrtimer_start(&ts->sched_timer, tick,

			      HRTIMER_MODE_ABS_PINNED_HARD);

	} else {

		hrtimer_set_expires(&ts->sched_timer, tick);

		tick_program_event(tick, 1);
@@ -1327,7 +1330,7 @@ void tick_setup_sched_timer(void) 
	/*

	 * Emulate tick processing via per-CPU hrtimers:

	 */

	hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);

	hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);

	ts->sched_timer.function = tick_sched_timer;



	/* Get the next period (per-CPU) */
@@ -1342,7 +1345,7 @@ void tick_setup_sched_timer(void) 
	}



	hrtimer_forward(&ts->sched_timer, now, tick_period);

	hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED);

	hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED_HARD);

	tick_nohz_activate(ts, NOHZ_MODE_HIGHRES);

}

#endif /* HIGH_RES_TIMERS */