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synced 2024-10-04 16:15:11 +00:00
ntp: handle leap second via timer
Remove the leap second handling from second_overflow(), which doesn't have to check for it every second anymore. With CONFIG_NO_HZ this also makes sure the leap second is handled close to the full second. Additionally this makes it possible to abort a leap second properly by resetting the STA_INS/STA_DEL status bits. Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Cc: john stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
8383c42399
commit
7dffa3c673
4 changed files with 96 additions and 46 deletions
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@ -93,6 +93,8 @@ struct clocksource {
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#endif
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#endif
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};
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};
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extern struct clocksource *clock; /* current clocksource */
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/*
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/*
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* Clock source flags bits::
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* Clock source flags bits::
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*/
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*/
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@ -212,6 +212,7 @@ extern long time_esterror; /* estimated error */
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extern long time_adjust; /* The amount of adjtime left */
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extern long time_adjust; /* The amount of adjtime left */
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extern void ntp_init(void);
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extern void ntp_clear(void);
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extern void ntp_clear(void);
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/**
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/**
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@ -16,6 +16,7 @@
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#include <linux/hrtimer.h>
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#include <linux/hrtimer.h>
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#include <linux/capability.h>
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#include <linux/capability.h>
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#include <linux/math64.h>
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#include <linux/math64.h>
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#include <linux/clocksource.h>
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#include <asm/timex.h>
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#include <asm/timex.h>
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/*
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/*
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@ -26,6 +27,8 @@ unsigned long tick_nsec; /* ACTHZ period (nsec) */
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u64 tick_length;
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u64 tick_length;
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static u64 tick_length_base;
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static u64 tick_length_base;
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static struct hrtimer leap_timer;
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#define MAX_TICKADJ 500 /* microsecs */
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#define MAX_TICKADJ 500 /* microsecs */
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#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
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#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
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NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
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NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
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@ -119,6 +122,54 @@ void ntp_clear(void)
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time_offset = 0;
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time_offset = 0;
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}
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}
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/*
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* Leap second processing. If in leap-insert state at the end of the
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* day, the system clock is set back one second; if in leap-delete
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* state, the system clock is set ahead one second.
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*/
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static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
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{
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enum hrtimer_restart res = HRTIMER_NORESTART;
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write_seqlock_irq(&xtime_lock);
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switch (time_state) {
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case TIME_OK:
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break;
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case TIME_INS:
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xtime.tv_sec--;
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wall_to_monotonic.tv_sec++;
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time_state = TIME_OOP;
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printk(KERN_NOTICE "Clock: "
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"inserting leap second 23:59:60 UTC\n");
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leap_timer.expires = ktime_add_ns(leap_timer.expires,
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NSEC_PER_SEC);
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res = HRTIMER_RESTART;
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break;
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case TIME_DEL:
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xtime.tv_sec++;
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time_tai--;
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wall_to_monotonic.tv_sec--;
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time_state = TIME_WAIT;
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printk(KERN_NOTICE "Clock: "
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"deleting leap second 23:59:59 UTC\n");
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break;
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case TIME_OOP:
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time_tai++;
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time_state = TIME_WAIT;
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/* fall through */
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case TIME_WAIT:
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if (!(time_status & (STA_INS | STA_DEL)))
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time_state = TIME_OK;
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break;
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}
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update_vsyscall(&xtime, clock);
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write_sequnlock_irq(&xtime_lock);
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return res;
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}
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/*
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/*
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* this routine handles the overflow of the microsecond field
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* this routine handles the overflow of the microsecond field
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*
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*
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@ -138,48 +189,6 @@ void second_overflow(void)
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time_status |= STA_UNSYNC;
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time_status |= STA_UNSYNC;
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}
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}
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/*
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* Leap second processing. If in leap-insert state at the end of the
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* day, the system clock is set back one second; if in leap-delete
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* state, the system clock is set ahead one second. The microtime()
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* routine or external clock driver will insure that reported time is
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* always monotonic. The ugly divides should be replaced.
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*/
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switch (time_state) {
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case TIME_OK:
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if (time_status & STA_INS)
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time_state = TIME_INS;
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else if (time_status & STA_DEL)
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time_state = TIME_DEL;
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break;
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case TIME_INS:
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if (xtime.tv_sec % 86400 == 0) {
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xtime.tv_sec--;
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wall_to_monotonic.tv_sec++;
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time_state = TIME_OOP;
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printk(KERN_NOTICE "Clock: inserting leap second "
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"23:59:60 UTC\n");
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}
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break;
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case TIME_DEL:
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if ((xtime.tv_sec + 1) % 86400 == 0) {
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xtime.tv_sec++;
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time_tai--;
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wall_to_monotonic.tv_sec--;
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time_state = TIME_WAIT;
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printk(KERN_NOTICE "Clock: deleting leap second "
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"23:59:59 UTC\n");
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}
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break;
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case TIME_OOP:
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time_tai++;
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time_state = TIME_WAIT;
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break;
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case TIME_WAIT:
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if (!(time_status & (STA_INS | STA_DEL)))
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time_state = TIME_OK;
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}
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/*
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/*
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* Compute the phase adjustment for the next second. The offset is
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* Compute the phase adjustment for the next second. The offset is
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* reduced by a fixed factor times the time constant.
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* reduced by a fixed factor times the time constant.
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@ -268,7 +277,7 @@ static inline void notify_cmos_timer(void) { }
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int do_adjtimex(struct timex *txc)
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int do_adjtimex(struct timex *txc)
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{
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{
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struct timespec ts;
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struct timespec ts;
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long save_adjust;
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long save_adjust, sec;
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int result;
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int result;
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/* In order to modify anything, you gotta be super-user! */
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/* In order to modify anything, you gotta be super-user! */
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@ -289,6 +298,10 @@ int do_adjtimex(struct timex *txc)
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txc->tick > 1100000/USER_HZ)
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txc->tick > 1100000/USER_HZ)
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return -EINVAL;
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return -EINVAL;
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if (time_state != TIME_OK && txc->modes & ADJ_STATUS)
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hrtimer_cancel(&leap_timer);
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getnstimeofday(&ts);
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write_seqlock_irq(&xtime_lock);
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write_seqlock_irq(&xtime_lock);
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/* Save for later - semantics of adjtime is to return old value */
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/* Save for later - semantics of adjtime is to return old value */
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@ -305,6 +318,34 @@ int do_adjtimex(struct timex *txc)
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/* only set allowed bits */
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/* only set allowed bits */
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time_status &= STA_RONLY;
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time_status &= STA_RONLY;
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time_status |= txc->status & ~STA_RONLY;
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time_status |= txc->status & ~STA_RONLY;
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switch (time_state) {
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case TIME_OK:
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start_timer:
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sec = ts.tv_sec;
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if (time_status & STA_INS) {
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time_state = TIME_INS;
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sec += 86400 - sec % 86400;
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hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
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} else if (time_status & STA_DEL) {
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time_state = TIME_DEL;
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sec += 86400 - (sec + 1) % 86400;
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hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
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}
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break;
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case TIME_INS:
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case TIME_DEL:
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time_state = TIME_OK;
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goto start_timer;
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break;
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case TIME_WAIT:
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if (!(time_status & (STA_INS | STA_DEL)))
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time_state = TIME_OK;
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break;
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case TIME_OOP:
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hrtimer_restart(&leap_timer);
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break;
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}
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}
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}
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if (txc->modes & ADJ_NANO)
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if (txc->modes & ADJ_NANO)
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@ -384,7 +425,6 @@ int do_adjtimex(struct timex *txc)
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txc->stbcnt = 0;
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txc->stbcnt = 0;
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write_sequnlock_irq(&xtime_lock);
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write_sequnlock_irq(&xtime_lock);
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getnstimeofday(&ts);
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txc->time.tv_sec = ts.tv_sec;
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txc->time.tv_sec = ts.tv_sec;
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txc->time.tv_usec = ts.tv_nsec;
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txc->time.tv_usec = ts.tv_nsec;
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if (!(time_status & STA_NANO))
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if (!(time_status & STA_NANO))
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@ -402,3 +442,10 @@ static int __init ntp_tick_adj_setup(char *str)
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}
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}
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__setup("ntp_tick_adj=", ntp_tick_adj_setup);
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__setup("ntp_tick_adj=", ntp_tick_adj_setup);
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void __init ntp_init(void)
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{
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ntp_clear();
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hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
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leap_timer.function = ntp_leap_second;
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}
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@ -53,7 +53,7 @@ void update_xtime_cache(u64 nsec)
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timespec_add_ns(&xtime_cache, nsec);
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timespec_add_ns(&xtime_cache, nsec);
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}
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}
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static struct clocksource *clock; /* pointer to current clocksource */
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struct clocksource *clock;
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#ifdef CONFIG_GENERIC_TIME
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#ifdef CONFIG_GENERIC_TIME
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@ -246,7 +246,7 @@ void __init timekeeping_init(void)
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write_seqlock_irqsave(&xtime_lock, flags);
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write_seqlock_irqsave(&xtime_lock, flags);
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ntp_clear();
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ntp_init();
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clock = clocksource_get_next();
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clock = clocksource_get_next();
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clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
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clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
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