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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: DengChao <chao.deng@linaro.org>
[jstultz: Tweaked commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
DengChao 2015-12-13 12:26:42 +08:00 committed by John Stultz
parent 0af864651b
commit c796348774
2 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
kernel/time/ntp.c
View File

@ -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;

2
kernel/time/ntp_internal.h
View File

@ -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 *);