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Commit 69239749 authored by Tony Lindgren's avatar Tony Lindgren Committed by Linus Torvalds
Browse files

[PATCH] fix next_timer_interrupt() for hrtimer 



Also from Thomas Gleixner <tglx@linutronix.de>

Function next_timer_interrupt() got broken with a recent patch
6ba1b912 as sys_nanosleep() was moved to
hrtimer.  This broke things as next_timer_interrupt() did not check hrtimer
tree for next event.

Function next_timer_interrupt() is needed with dyntick (CONFIG_NO_IDLE_HZ,
VST) implementations, as the system can be in idle when next hrtimer event
was supposed to happen.  At least ARM and S390 currently use
next_timer_interrupt().

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f7c09bd9

arch/arm/kernel/time.c

+6 −4
Original line number Diff line number Diff line
@@ -422,12 +422,14 @@ static int timer_dyn_tick_disable(void) 
void timer_dyn_reprogram(void)

{

	struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;

	unsigned long next, seq;



	if (dyn_tick) {

		write_seqlock(&xtime_lock);

		if (dyn_tick->state & DYN_TICK_ENABLED)

	if (dyn_tick && (dyn_tick->state & DYN_TICK_ENABLED)) {

		next = next_timer_interrupt();

		do {

			seq = read_seqbegin(&xtime_lock);

			dyn_tick->reprogram(next_timer_interrupt() - jiffies);

		write_sequnlock(&xtime_lock);

		} while (read_seqretry(&xtime_lock, seq));

	}

}

include/linux/hrtimer.h

+4 −0
Original line number Diff line number Diff line
@@ -116,6 +116,10 @@ extern int hrtimer_try_to_cancel(struct hrtimer *timer); 
extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);

extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);



#ifdef CONFIG_NO_IDLE_HZ

extern ktime_t hrtimer_get_next_event(void);

#endif



static inline int hrtimer_active(const struct hrtimer *timer)

{

	return timer->state == HRTIMER_PENDING;

kernel/hrtimer.c

+35 −0
Original line number Diff line number Diff line
@@ -505,6 +505,41 @@ ktime_t hrtimer_get_remaining(const struct hrtimer *timer) 
	return rem;

}



#ifdef CONFIG_NO_IDLE_HZ

/**

 * hrtimer_get_next_event - get the time until next expiry event

 *

 * Returns the delta to the next expiry event or KTIME_MAX if no timer

 * is pending.

 */

ktime_t hrtimer_get_next_event(void)

{

	struct hrtimer_base *base = __get_cpu_var(hrtimer_bases);

	ktime_t delta, mindelta = { .tv64 = KTIME_MAX };

	unsigned long flags;

	int i;



	for (i = 0; i < MAX_HRTIMER_BASES; i++, base++) {

		struct hrtimer *timer;



		spin_lock_irqsave(&base->lock, flags);

		if (!base->first) {

			spin_unlock_irqrestore(&base->lock, flags);

			continue;

		}

		timer = rb_entry(base->first, struct hrtimer, node);

		delta.tv64 = timer->expires.tv64;

		spin_unlock_irqrestore(&base->lock, flags);

		delta = ktime_sub(delta, base->get_time());

		if (delta.tv64 < mindelta.tv64)

			mindelta.tv64 = delta.tv64;

	}

	if (mindelta.tv64 < 0)

		mindelta.tv64 = 0;

	return mindelta;

}

#endif



/**

 * hrtimer_init - initialize a timer to the given clock

 *

kernel/timer.c

+16 −0
Original line number Diff line number Diff line
@@ -489,9 +489,21 @@ unsigned long next_timer_interrupt(void) 
	struct list_head *list;

	struct timer_list *nte;

	unsigned long expires;

	unsigned long hr_expires = MAX_JIFFY_OFFSET;

	ktime_t hr_delta;

	tvec_t *varray[4];

	int i, j;



	hr_delta = hrtimer_get_next_event();

	if (hr_delta.tv64 != KTIME_MAX) {

		struct timespec tsdelta;

		tsdelta = ktime_to_timespec(hr_delta);

		hr_expires = timespec_to_jiffies(&tsdelta);

		if (hr_expires < 3)

			return hr_expires + jiffies;

	}

	hr_expires += jiffies;



	base = &__get_cpu_var(tvec_bases);

	spin_lock(&base->t_base.lock);

	expires = base->timer_jiffies + (LONG_MAX >> 1);
@@ -542,6 +554,10 @@ unsigned long next_timer_interrupt(void) 
		}

	}

	spin_unlock(&base->t_base.lock);



	if (time_before(hr_expires, expires))

		return hr_expires;



	return expires;

}

#endif