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tick: Mark tick related hrtimers to expiry in hard interrupt context

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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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.459144407@linutronix.de
This commit is contained in:
Sebastian Andrzej Siewior 2019-07-26 20:30:56 +02:00 committed by Thomas Gleixner
parent 2c0d278f32
commit 902a9f9c50
2 changed files with 18 additions and 10 deletions
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13
kernel/time/tick-broadcast-hrtimer.c
View File

@ -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);
}

15
kernel/time/tick-sched.c
View File

@ -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 */