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Commit 8cf4e750 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Thomas Gleixner
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clocksource: Delay clocksource watchdog highres enablement 



The clocksource watchdog marks a clock as highres capable before it
checked the deviation from the watchdog clocksource even for a single
time. Make sure that the deviation is at least checked once before
doing the switch to highres mode.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
LKML-Reference: <20090814134808.627795883@de.ibm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent f1b82746

kernel/time/clocksource.c

+22 −25
Original line number Diff line number Diff line
@@ -153,11 +153,8 @@ static unsigned long watchdog_resumed; 
#define WATCHDOG_INTERVAL (HZ >> 1)

#define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4)



static void clocksource_ratewd(struct clocksource *cs, int64_t delta)

static void clocksource_unstable(struct clocksource *cs, int64_t delta)

{

	if (delta > -WATCHDOG_THRESHOLD && delta < WATCHDOG_THRESHOLD)

		return;



	printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",

	       cs->name, delta);

	cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
@@ -183,32 +180,32 @@ static void clocksource_watchdog(unsigned long data) 
	list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) {

		csnow = cs->read(cs);



		if (unlikely(resumed)) {

		/* Clocksource initialized ? */

		if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) {

			cs->flags |= CLOCK_SOURCE_WATCHDOG;

			cs->wd_last = csnow;

			continue;

		}



		/* Initialized ? */

		if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) {

			if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) &&

		/* Check the deviation from the watchdog clocksource. */

		cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask);

		cs->wd_last = csnow;

		if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) {

			clocksource_unstable(cs, cs_nsec - wd_nsec);

			continue;

		}



		if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) &&

		    (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) &&

		    (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) {

			cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;

			/*

				 * We just marked the clocksource as

				 * highres-capable, notify the rest of the

				 * system as well so that we transition

				 * into high-res mode:

			 * We just marked the clocksource as highres-capable,

			 * notify the rest of the system as well so that we

			 * transition into high-res mode:

			 */

			tick_clock_notify();

		}

			cs->flags |= CLOCK_SOURCE_WATCHDOG;

			cs->wd_last = csnow;

		} else {

			cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask);

			cs->wd_last = csnow;

			/* Check the delta. Might remove from the list ! */

			clocksource_ratewd(cs, cs_nsec - wd_nsec);

		}

	}



	if (!list_empty(&watchdog_list)) {