Commit c7963487 authored by DengChao's avatar DengChao Committed by John Stultz
Browse files

ntp: Fix second_overflow's input parameter type to be 64bits 



The function "second_overflow" uses "unsign long"
as its input parameter type which will overflow after
year 2106 on 32bit systems.

Thus this patch replaces it with time64_t type.

While the 64-bit division is expensive, "next_ntp_leap_sec"
has been calculated already, so we can just re-use it in the
TIME_INS/DEL cases, allowing one expensive division per
leapsecond instead of re-doing the divsion once a second after
the leap flag has been set.

Signed-off-by: default avatarDengChao <chao.deng@linaro.org>
[jstultz: Tweaked commit message]
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 0af86465

kernel/time/ntp.c

+9 −7
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/mm.h>

#include <linux/module.h>

#include <linux/rtc.h>

#include <linux/math64.h>



#include "ntp_internal.h"

#include "timekeeping_internal.h"
@@ -394,10 +395,11 @@ ktime_t ntp_get_next_leap(void) 
 *

 * Also handles leap second processing, and returns leap offset

 */

int second_overflow(unsigned long secs)

int second_overflow(time64_t secs)

{

	s64 delta;

	int leap = 0;

	s32 rem;



	/*

	 * Leap second processing. If in leap-insert state at the end of the
@@ -408,19 +410,19 @@ int second_overflow(unsigned long secs) 
	case TIME_OK:

		if (time_status & STA_INS) {

			time_state = TIME_INS;

			ntp_next_leap_sec = secs + SECS_PER_DAY -

						(secs % SECS_PER_DAY);

			div_s64_rem(secs, SECS_PER_DAY, &rem);

			ntp_next_leap_sec = secs + SECS_PER_DAY - rem;

		} else if (time_status & STA_DEL) {

			time_state = TIME_DEL;

			ntp_next_leap_sec = secs + SECS_PER_DAY -

						 ((secs+1) % SECS_PER_DAY);

			div_s64_rem(secs + 1, SECS_PER_DAY, &rem);

			ntp_next_leap_sec = secs + SECS_PER_DAY - rem;

		}

		break;

	case TIME_INS:

		if (!(time_status & STA_INS)) {

			ntp_next_leap_sec = TIME64_MAX;

			time_state = TIME_OK;

		} else if (secs % SECS_PER_DAY == 0) {

		} else if (secs == ntp_next_leap_sec) {

			leap = -1;

			time_state = TIME_OOP;

			printk(KERN_NOTICE
@@ -431,7 +433,7 @@ int second_overflow(unsigned long secs) 
		if (!(time_status & STA_DEL)) {

			ntp_next_leap_sec = TIME64_MAX;

			time_state = TIME_OK;

		} else if ((secs + 1) % SECS_PER_DAY == 0) {

		} else if (secs == ntp_next_leap_sec) {

			leap = 1;

			ntp_next_leap_sec = TIME64_MAX;

			time_state = TIME_WAIT;

kernel/time/ntp_internal.h

+1 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ extern void ntp_clear(void); 
/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */

extern u64 ntp_tick_length(void);

extern ktime_t ntp_get_next_leap(void);

extern int second_overflow(unsigned long secs);

extern int second_overflow(time64_t secs);

extern int ntp_validate_timex(struct timex *);

extern int __do_adjtimex(struct timex *, struct timespec64 *, s32 *);

extern void __hardpps(const struct timespec64 *, const struct timespec64 *);

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