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>

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index e947bfddd2c27820861f2c400268347f767f98a2..36f2ca09aa5e458bf1f31e3ec018e180dcc5b345 100644 (file)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -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;

diff --git a/kernel/time/ntp_internal.h b/kernel/time/ntp_internal.h
index af924470eac04c046e3481750a32833cef9acc13..d8a7c11fa71a51e09063cf807d6f59959a6119ab 100644 (file)
--- a/kernel/time/ntp_internal.h
+++ b/kernel/time/ntp_internal.h
@@ -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 *);