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Commit bd331268 authored by John Stultz's avatar John Stultz
Browse files

ntp: Add ntp_lock to replace xtime_locking 



Use a ntp_lock spin lock to replace xtime_lock locking in ntp.c

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 ea7cf49a

kernel/time/ntp.c

+44 −19
Original line number Diff line number Diff line
@@ -22,6 +22,9 @@ 
 * NTP timekeeping variables:

 */



DEFINE_SPINLOCK(ntp_lock);





/* USER_HZ period (usecs): */

unsigned long			tick_usec = TICK_USEC;
@@ -133,7 +136,7 @@ static inline void pps_reset_freq_interval(void) 
/**

 * pps_clear - Clears the PPS state variables

 *

 * Must be called while holding a write on the xtime_lock

 * Must be called while holding a write on the ntp_lock

 */

static inline void pps_clear(void)

{
@@ -149,7 +152,7 @@ static inline void pps_clear(void) 
 * the last PPS signal. When it reaches 0, indicate that PPS signal is

 * missing.

 *

 * Must be called while holding a write on the xtime_lock

 * Must be called while holding a write on the ntp_lock

 */

static inline void pps_dec_valid(void)

{
@@ -341,11 +344,13 @@ static void ntp_update_offset(long offset) 


/**

 * ntp_clear - Clears the NTP state variables

 *

 * Must be called while holding a write on the xtime_lock

 */

void ntp_clear(void)

{

	unsigned long flags;



	spin_lock_irqsave(&ntp_lock, flags);



	time_adjust	= 0;		/* stop active adjtime() */

	time_status	|= STA_UNSYNC;

	time_maxerror	= NTP_PHASE_LIMIT;
@@ -358,12 +363,20 @@ void ntp_clear(void) 


	/* Clear PPS state variables */

	pps_clear();

	spin_unlock_irqrestore(&ntp_lock, flags);



}





u64 ntp_tick_length(void)

{

	return tick_length;

	unsigned long flags;

	s64 ret;



	spin_lock_irqsave(&ntp_lock, flags);

	ret = tick_length;

	spin_unlock_irqrestore(&ntp_lock, flags);

	return ret;

}
@@ -375,14 +388,15 @@ u64 ntp_tick_length(void) 
static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)

{

	enum hrtimer_restart res = HRTIMER_NORESTART;

	unsigned long flags;

	int leap = 0;



	write_seqlock(&xtime_lock);



	spin_lock_irqsave(&ntp_lock, flags);

	switch (time_state) {

	case TIME_OK:

		break;

	case TIME_INS:

		timekeeping_leap_insert(-1);

		leap = -1;

		time_state = TIME_OOP;

		printk(KERN_NOTICE

			"Clock: inserting leap second 23:59:60 UTC\n");
@@ -390,7 +404,7 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer) 
		res = HRTIMER_RESTART;

		break;

	case TIME_DEL:

		timekeeping_leap_insert(1);

		leap = 1;

		time_tai--;

		time_state = TIME_WAIT;

		printk(KERN_NOTICE
@@ -405,8 +419,14 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer) 
			time_state = TIME_OK;

		break;

	}

	spin_unlock_irqrestore(&ntp_lock, flags);



	write_sequnlock(&xtime_lock);

	/*

	 * We have to call this outside of the ntp_lock to keep

	 * the proper locking hierarchy

	 */

	if (leap)

		timekeeping_leap_insert(leap);



	return res;

}
@@ -422,6 +442,9 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer) 
void second_overflow(void)

{

	s64 delta;

	unsigned long flags;



	spin_lock_irqsave(&ntp_lock, flags);



	/* Bump the maxerror field */

	time_maxerror += MAXFREQ / NSEC_PER_USEC;
@@ -441,23 +464,25 @@ void second_overflow(void) 
	pps_dec_valid();



	if (!time_adjust)

		return;

		goto out;



	if (time_adjust > MAX_TICKADJ) {

		time_adjust -= MAX_TICKADJ;

		tick_length += MAX_TICKADJ_SCALED;

		return;

		goto out;

	}



	if (time_adjust < -MAX_TICKADJ) {

		time_adjust += MAX_TICKADJ;

		tick_length -= MAX_TICKADJ_SCALED;

		return;

		goto out;

	}



	tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)

							 << NTP_SCALE_SHIFT;

	time_adjust = 0;

out:

	spin_unlock_irqrestore(&ntp_lock, flags);

}



#ifdef CONFIG_GENERIC_CMOS_UPDATE
@@ -681,7 +706,7 @@ int do_adjtimex(struct timex *txc) 


	getnstimeofday(&ts);



	write_seqlock_irq(&xtime_lock);

	spin_lock_irq(&ntp_lock);



	if (txc->modes & ADJ_ADJTIME) {

		long save_adjust = time_adjust;
@@ -723,7 +748,7 @@ int do_adjtimex(struct timex *txc) 
	/* fill PPS status fields */

	pps_fill_timex(txc);



	write_sequnlock_irq(&xtime_lock);

	spin_unlock_irq(&ntp_lock);



	txc->time.tv_sec = ts.tv_sec;

	txc->time.tv_usec = ts.tv_nsec;
@@ -921,7 +946,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) 


	pts_norm = pps_normalize_ts(*phase_ts);



	write_seqlock_irqsave(&xtime_lock, flags);

	spin_lock_irqsave(&ntp_lock, flags);



	/* clear the error bits, they will be set again if needed */

	time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
@@ -934,7 +959,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) 
	 * just start the frequency interval */

	if (unlikely(pps_fbase.tv_sec == 0)) {

		pps_fbase = *raw_ts;

		write_sequnlock_irqrestore(&xtime_lock, flags);

		spin_unlock_irqrestore(&ntp_lock, flags);

		return;

	}
@@ -949,7 +974,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) 
		time_status |= STA_PPSJITTER;

		/* restart the frequency calibration interval */

		pps_fbase = *raw_ts;

		write_sequnlock_irqrestore(&xtime_lock, flags);

		spin_unlock_irqrestore(&ntp_lock, flags);

		pr_err("hardpps: PPSJITTER: bad pulse\n");

		return;

	}
@@ -966,7 +991,7 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) 


	hardpps_update_phase(pts_norm.nsec);



	write_sequnlock_irqrestore(&xtime_lock, flags);

	spin_unlock_irqrestore(&ntp_lock, flags);

}

EXPORT_SYMBOL(hardpps);