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Commit b52f52a0 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Linus Torvalds
Browse files

clocksource: fix resume logic 



We need to make sure that the clocksources are resumed, when timekeeping is
resumed.  The current resume logic does not guarantee this.

Add a resume function pointer to the clocksource struct, so clocksource
drivers which need to reinitialize the clocksource can provide a resume
function.

Add a resume function, which calls the maybe available clocksource resume
functions and resets the watchdog function, so a stable TSC can be used
accross suspend/resume.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4037d452

include/linux/clocksource.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -49,6 +49,7 @@ struct clocksource; 
 * @shift:		cycle to nanosecond divisor (power of two)

 * @shift:		cycle to nanosecond divisor (power of two)

 * @flags:		flags describing special properties

 * @flags:		flags describing special properties

 * @vread:		vsyscall based read

 * @vread:		vsyscall based read

 * @resume:		resume function for the clocksource, if necessary

 * @cycle_interval:	Used internally by timekeeping core, please ignore.

 * @cycle_interval:	Used internally by timekeeping core, please ignore.

 * @xtime_interval:	Used internally by timekeeping core, please ignore.

 * @xtime_interval:	Used internally by timekeeping core, please ignore.

 */

 */
@@ -65,6 +66,7 @@ struct clocksource { 
	u32 shift;

	u32 shift;

	unsigned long flags;

	unsigned long flags;

	cycle_t (*vread)(void);

	cycle_t (*vread)(void);

	void (*resume)(void);





	/* timekeeping specific data, ignore */

	/* timekeeping specific data, ignore */

	cycle_t cycle_interval;

	cycle_t cycle_interval;
@@ -209,6 +211,7 @@ static inline void clocksource_calculate_interval(struct clocksource *c, 
extern int clocksource_register(struct clocksource*);

extern int clocksource_register(struct clocksource*);

extern struct clocksource* clocksource_get_next(void);

extern struct clocksource* clocksource_get_next(void);

extern void clocksource_change_rating(struct clocksource *cs, int rating);

extern void clocksource_change_rating(struct clocksource *cs, int rating);

extern void clocksource_resume(void);





#ifdef CONFIG_GENERIC_TIME_VSYSCALL

#ifdef CONFIG_GENERIC_TIME_VSYSCALL

extern void update_vsyscall(struct timespec *ts, struct clocksource *c);

extern void update_vsyscall(struct timespec *ts, struct clocksource *c);

kernel/time/clocksource.c

+45 −0
Original line number Original line Diff line number Diff line
@@ -74,6 +74,8 @@ static struct clocksource *watchdog; 
static struct timer_list watchdog_timer;

static struct timer_list watchdog_timer;

static DEFINE_SPINLOCK(watchdog_lock);

static DEFINE_SPINLOCK(watchdog_lock);

static cycle_t watchdog_last;

static cycle_t watchdog_last;

static int watchdog_resumed;



/*

/*

 * Interval: 0.5sec Threshold: 0.0625s

 * Interval: 0.5sec Threshold: 0.0625s

 */

 */
@@ -98,15 +100,26 @@ static void clocksource_watchdog(unsigned long data) 
	struct clocksource *cs, *tmp;

	struct clocksource *cs, *tmp;

	cycle_t csnow, wdnow;

	cycle_t csnow, wdnow;

	int64_t wd_nsec, cs_nsec;

	int64_t wd_nsec, cs_nsec;

	int resumed;





	spin_lock(&watchdog_lock);

	spin_lock(&watchdog_lock);





	resumed = watchdog_resumed;

	if (unlikely(resumed))

		watchdog_resumed = 0;



	wdnow = watchdog->read();

	wdnow = watchdog->read();

	wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);

	wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);

	watchdog_last = wdnow;

	watchdog_last = wdnow;





	list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) {

	list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) {

		csnow = cs->read();

		csnow = cs->read();



		if (unlikely(resumed)) {

			cs->wd_last = csnow;

			continue;

		}



		/* Initialized ? */

		/* Initialized ? */

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

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

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

			if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) &&
@@ -136,6 +149,13 @@ static void clocksource_watchdog(unsigned long data) 
	}

	}

	spin_unlock(&watchdog_lock);

	spin_unlock(&watchdog_lock);

}

}

static void clocksource_resume_watchdog(void)

{

	spin_lock(&watchdog_lock);

	watchdog_resumed = 1;

	spin_unlock(&watchdog_lock);

}



static void clocksource_check_watchdog(struct clocksource *cs)

static void clocksource_check_watchdog(struct clocksource *cs)

{

{

	struct clocksource *cse;

	struct clocksource *cse;
@@ -182,8 +202,33 @@ static void clocksource_check_watchdog(struct clocksource *cs) 
	if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)

	if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)

		cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;

		cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;

}

}



static inline void clocksource_resume_watchdog(void) { }

#endif

#endif





/**

 * clocksource_resume - resume the clocksource(s)

 */

void clocksource_resume(void)

{

	struct list_head *tmp;

	unsigned long flags;



	spin_lock_irqsave(&clocksource_lock, flags);



	list_for_each(tmp, &clocksource_list) {

		struct clocksource *cs;



		cs = list_entry(tmp, struct clocksource, list);

		if (cs->resume)

			cs->resume();

	}



	clocksource_resume_watchdog();



	spin_unlock_irqrestore(&clocksource_lock, flags);

}



/**

/**

 * clocksource_get_next - Returns the selected clocksource

 * clocksource_get_next - Returns the selected clocksource

 *

 *

kernel/timer.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -1499,6 +1499,8 @@ unregister_time_interpolator(struct time_interpolator *ti) 
		prev = &curr->next;

		prev = &curr->next;

	}

	}





	clocksource_resume();



	write_seqlock_irqsave(&xtime_lock, flags);

	write_seqlock_irqsave(&xtime_lock, flags);

	if (ti == time_interpolator) {

	if (ti == time_interpolator) {

		/* we lost the best time-interpolator: */

		/* we lost the best time-interpolator: */