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Commit 70471f2f authored by John Stultz's avatar John Stultz
Browse files

time: Add timekeeper lock 



Now that all the timekeeping variables are stored in
the timekeeper structure, add a new lock to protect the
structure.

For now, this lock nests under the xtime_lock for writes.

For readers, we don't need to take xtime_lock anymore.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 8fcce546

kernel/time/timekeeping.c

+82 −44
Original line number Diff line number Diff line
@@ -69,6 +69,9 @@ struct timekeeper { 
	struct timespec total_sleep_time;

	/* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */

	struct timespec raw_time;



	/* Seqlock for all timekeeper values */

	seqlock_t lock;

};



static struct timekeeper timekeeper;
@@ -172,10 +175,17 @@ static inline s64 timekeeping_get_ns_raw(void) 
/* must hold xtime_lock */

void timekeeping_leap_insert(int leapsecond)

{

	unsigned long flags;



	write_seqlock_irqsave(&timekeeper.lock, flags);



	timekeeper.xtime.tv_sec += leapsecond;

	timekeeper.wall_to_monotonic.tv_sec -= leapsecond;

	update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,

			 timekeeper.clock, timekeeper.mult);



	write_sequnlock_irqrestore(&timekeeper.lock, flags);



}



/**
@@ -222,7 +232,7 @@ void getnstimeofday(struct timespec *ts) 
	WARN_ON(timekeeping_suspended);



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);



		*ts = timekeeper.xtime;

		nsecs = timekeeping_get_ns();
@@ -230,7 +240,7 @@ void getnstimeofday(struct timespec *ts) 
		/* If arch requires, add in gettimeoffset() */

		nsecs += arch_gettimeoffset();



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

	} while (read_seqretry(&timekeeper.lock, seq));



	timespec_add_ns(ts, nsecs);

}
@@ -245,7 +255,7 @@ ktime_t ktime_get(void) 
	WARN_ON(timekeeping_suspended);



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);

		secs = timekeeper.xtime.tv_sec +

				timekeeper.wall_to_monotonic.tv_sec;

		nsecs = timekeeper.xtime.tv_nsec +
@@ -254,7 +264,7 @@ ktime_t ktime_get(void) 
		/* If arch requires, add in gettimeoffset() */

		nsecs += arch_gettimeoffset();



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

	} while (read_seqretry(&timekeeper.lock, seq));

	/*

	 * Use ktime_set/ktime_add_ns to create a proper ktime on

	 * 32-bit architectures without CONFIG_KTIME_SCALAR.
@@ -280,14 +290,14 @@ void ktime_get_ts(struct timespec *ts) 
	WARN_ON(timekeeping_suspended);



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);

		*ts = timekeeper.xtime;

		tomono = timekeeper.wall_to_monotonic;

		nsecs = timekeeping_get_ns();

		/* If arch requires, add in gettimeoffset() */

		nsecs += arch_gettimeoffset();



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

	} while (read_seqretry(&timekeeper.lock, seq));



	set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,

				ts->tv_nsec + tomono.tv_nsec + nsecs);
@@ -315,7 +325,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real) 
	do {

		u32 arch_offset;



		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);



		*ts_raw = timekeeper.raw_time;

		*ts_real = timekeeper.xtime;
@@ -328,7 +338,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real) 
		nsecs_raw += arch_offset;

		nsecs_real += arch_offset;



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

	} while (read_seqretry(&timekeeper.lock, seq));



	timespec_add_ns(ts_raw, nsecs_raw);

	timespec_add_ns(ts_real, nsecs_real);
@@ -362,12 +372,13 @@ EXPORT_SYMBOL(do_gettimeofday); 
int do_settimeofday(const struct timespec *tv)

{

	struct timespec ts_delta;

	unsigned long flags;

	unsigned long flags1,flags2;



	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)

		return -EINVAL;



	write_seqlock_irqsave(&xtime_lock, flags);

	write_seqlock_irqsave(&xtime_lock, flags1);

	write_seqlock_irqsave(&timekeeper.lock, flags2);



	timekeeping_forward_now();
@@ -384,7 +395,8 @@ int do_settimeofday(const struct timespec *tv) 
	update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,

			timekeeper.clock, timekeeper.mult);



	write_sequnlock_irqrestore(&xtime_lock, flags);

	write_sequnlock_irqrestore(&timekeeper.lock, flags2);

	write_sequnlock_irqrestore(&xtime_lock, flags1);



	/* signal hrtimers about time change */

	clock_was_set();
@@ -403,12 +415,13 @@ EXPORT_SYMBOL(do_settimeofday); 
 */

int timekeeping_inject_offset(struct timespec *ts)

{

	unsigned long flags;

	unsigned long flags1,flags2;



	if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)

		return -EINVAL;



	write_seqlock_irqsave(&xtime_lock, flags);

	write_seqlock_irqsave(&xtime_lock, flags1);

	write_seqlock_irqsave(&timekeeper.lock, flags2);



	timekeeping_forward_now();
@@ -422,7 +435,8 @@ int timekeeping_inject_offset(struct timespec *ts) 
	update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,

			timekeeper.clock, timekeeper.mult);



	write_sequnlock_irqrestore(&xtime_lock, flags);

	write_sequnlock_irqrestore(&timekeeper.lock, flags2);

	write_sequnlock_irqrestore(&xtime_lock, flags1);



	/* signal hrtimers about time change */

	clock_was_set();
@@ -494,11 +508,11 @@ void getrawmonotonic(struct timespec *ts) 
	s64 nsecs;



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);

		nsecs = timekeeping_get_ns_raw();

		*ts = timekeeper.raw_time;



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

	} while (read_seqretry(&timekeeper.lock, seq));



	timespec_add_ns(ts, nsecs);

}
@@ -514,24 +528,30 @@ int timekeeping_valid_for_hres(void) 
	int ret;



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);



		ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;



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

	} while (read_seqretry(&timekeeper.lock, seq));



	return ret;

}



/**

 * timekeeping_max_deferment - Returns max time the clocksource can be deferred

 *

 * Caller must observe xtime_lock via read_seqbegin/read_seqretry to

 * ensure that the clocksource does not change!

 */

u64 timekeeping_max_deferment(void)

{

	return timekeeper.clock->max_idle_ns;

	unsigned long seq;

	u64 ret;

	do {

		seq = read_seqbegin(&timekeeper.lock);



		ret = timekeeper.clock->max_idle_ns;



	} while (read_seqretry(&timekeeper.lock, seq));



	return ret;

}



/**
@@ -576,10 +596,13 @@ void __init timekeeping_init(void) 
	read_persistent_clock(&now);

	read_boot_clock(&boot);



	write_seqlock_irqsave(&xtime_lock, flags);

	seqlock_init(&timekeeper.lock);



	write_seqlock_irqsave(&xtime_lock, flags);

	ntp_init();

	write_sequnlock_irqrestore(&xtime_lock, flags);



	write_seqlock_irqsave(&timekeeper.lock, flags);

	clock = clocksource_default_clock();

	if (clock->enable)

		clock->enable(clock);
@@ -597,7 +620,7 @@ void __init timekeeping_init(void) 
				-boot.tv_sec, -boot.tv_nsec);

	timekeeper.total_sleep_time.tv_sec = 0;

	timekeeper.total_sleep_time.tv_nsec = 0;

	write_sequnlock_irqrestore(&xtime_lock, flags);

	write_sequnlock_irqrestore(&timekeeper.lock, flags);

}



/* time in seconds when suspend began */
@@ -638,7 +661,7 @@ static void __timekeeping_inject_sleeptime(struct timespec *delta) 
 */

void timekeeping_inject_sleeptime(struct timespec *delta)

{

	unsigned long flags;

	unsigned long flags1,flags2;

	struct timespec ts;



	/* Make sure we don't set the clock twice */
@@ -646,7 +669,9 @@ void timekeeping_inject_sleeptime(struct timespec *delta) 
	if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))

		return;



	write_seqlock_irqsave(&xtime_lock, flags);

	write_seqlock_irqsave(&xtime_lock, flags1);

	write_seqlock_irqsave(&timekeeper.lock, flags2);



	timekeeping_forward_now();



	__timekeeping_inject_sleeptime(delta);
@@ -656,7 +681,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta) 
	update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,

			timekeeper.clock, timekeeper.mult);



	write_sequnlock_irqrestore(&xtime_lock, flags);

	write_sequnlock_irqrestore(&timekeeper.lock, flags2);

	write_sequnlock_irqrestore(&xtime_lock, flags1);



	/* signal hrtimers about time change */

	clock_was_set();
@@ -672,14 +698,15 @@ void timekeeping_inject_sleeptime(struct timespec *delta) 
 */

static void timekeeping_resume(void)

{

	unsigned long flags;

	unsigned long flags1,flags2;

	struct timespec ts;



	read_persistent_clock(&ts);



	clocksource_resume();



	write_seqlock_irqsave(&xtime_lock, flags);

	write_seqlock_irqsave(&xtime_lock, flags1);

	write_seqlock_irqsave(&timekeeper.lock, flags2);



	if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {

		ts = timespec_sub(ts, timekeeping_suspend_time);
@@ -689,7 +716,8 @@ static void timekeeping_resume(void) 
	timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);

	timekeeper.ntp_error = 0;

	timekeeping_suspended = 0;

	write_sequnlock_irqrestore(&xtime_lock, flags);

	write_sequnlock_irqrestore(&timekeeper.lock, flags2);

	write_sequnlock_irqrestore(&xtime_lock, flags1);



	touch_softlockup_watchdog();
@@ -701,13 +729,14 @@ static void timekeeping_resume(void) 


static int timekeeping_suspend(void)

{

	unsigned long flags;

	unsigned long flags1,flags2;

	struct timespec		delta, delta_delta;

	static struct timespec	old_delta;



	read_persistent_clock(&timekeeping_suspend_time);



	write_seqlock_irqsave(&xtime_lock, flags);

	write_seqlock_irqsave(&xtime_lock, flags1);

	write_seqlock_irqsave(&timekeeper.lock, flags2);

	timekeeping_forward_now();

	timekeeping_suspended = 1;
@@ -730,7 +759,8 @@ static int timekeeping_suspend(void) 
		timekeeping_suspend_time =

			timespec_add(timekeeping_suspend_time, delta_delta);

	}

	write_sequnlock_irqrestore(&xtime_lock, flags);

	write_sequnlock_irqrestore(&timekeeper.lock, flags2);

	write_sequnlock_irqrestore(&xtime_lock, flags1);



	clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);

	clocksource_suspend();
@@ -983,10 +1013,13 @@ static void update_wall_time(void) 
	struct clocksource *clock;

	cycle_t offset;

	int shift = 0, maxshift;

	unsigned long flags;



	write_seqlock_irqsave(&timekeeper.lock, flags);



	/* Make sure we're fully resumed: */

	if (unlikely(timekeeping_suspended))

		return;

		goto out;



	clock = timekeeper.clock;
@@ -1067,6 +1100,10 @@ static void update_wall_time(void) 
	/* check to see if there is a new clocksource to use */

	update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,

			timekeeper.clock, timekeeper.mult);



out:

	write_sequnlock_irqrestore(&timekeeper.lock, flags);



}



/**
@@ -1112,13 +1149,13 @@ void get_monotonic_boottime(struct timespec *ts) 
	WARN_ON(timekeeping_suspended);



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);

		*ts = timekeeper.xtime;

		tomono = timekeeper.wall_to_monotonic;

		sleep = timekeeper.total_sleep_time;

		nsecs = timekeeping_get_ns();



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

	} while (read_seqretry(&timekeeper.lock, seq));



	set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,

			ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
@@ -1169,10 +1206,10 @@ struct timespec current_kernel_time(void) 
	unsigned long seq;



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);



		now = timekeeper.xtime;

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

	} while (read_seqretry(&timekeeper.lock, seq));



	return now;

}
@@ -1184,11 +1221,11 @@ struct timespec get_monotonic_coarse(void) 
	unsigned long seq;



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);



		now = timekeeper.xtime;

		mono = timekeeper.wall_to_monotonic;

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

	} while (read_seqretry(&timekeeper.lock, seq));



	set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,

				now.tv_nsec + mono.tv_nsec);
@@ -1220,11 +1257,11 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim, 
	unsigned long seq;



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);

		*xtim = timekeeper.xtime;

		*wtom = timekeeper.wall_to_monotonic;

		*sleep = timekeeper.total_sleep_time;

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

	} while (read_seqretry(&timekeeper.lock, seq));

}



/**
@@ -1236,9 +1273,10 @@ ktime_t ktime_get_monotonic_offset(void) 
	struct timespec wtom;



	do {

		seq = read_seqbegin(&xtime_lock);

		seq = read_seqbegin(&timekeeper.lock);

		wtom = timekeeper.wall_to_monotonic;

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

	} while (read_seqretry(&timekeeper.lock, seq));



	return timespec_to_ktime(wtom);

}