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Subject[RFC PATCH v2 04/11] time: Add rtc_time_to_tm64() safe version(using time64_t)
Date
As part of addressing 2038 saftey for in-kernel uses, this patch
adds safe rtc_time_to_tm64() using time64_t. After this patch,
rtc_time_to_tm() should be replaced by rtc_time_to_tm64() one by
one. Eventually, rtc_time_to_tm() will be removed from the kernel
when it has no users.

Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
---
drivers/rtc/rtc-lib.c | 20 ++++++++++++++++----
include/linux/rtc.h | 1 +
2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
index 6948cbd..e84e3a0 100644
--- a/drivers/rtc/rtc-lib.c
+++ b/drivers/rtc/rtc-lib.c
@@ -45,15 +45,17 @@ int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
}
EXPORT_SYMBOL(rtc_year_days);

+
/*
* Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
+ * Safe version for 2038 safety.
*/
-void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
+void rtc_time_to_tm64(time64_t time, struct rtc_time *tm)
{
unsigned int month, year;
int days;

- days = time / 86400;
+ days = div_s64(time, 86400);
time -= (unsigned int) days * 86400;

/* day of the week, 1970-01-01 was a Thursday */
@@ -81,13 +83,23 @@ void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
tm->tm_mon = month;
tm->tm_mday = days + 1;

- tm->tm_hour = time / 3600;
+ tm->tm_hour = div_s64(time, 3600);
time -= tm->tm_hour * 3600;
- tm->tm_min = time / 60;
+ tm->tm_min = div_s64(time, 60);
tm->tm_sec = time - tm->tm_min * 60;

tm->tm_isdst = 0;
}
+EXPORT_SYMBOL(rtc_time_to_tm64);
+
+/* TODO: [2038 safety] should be replaced by rtc_time_to_tm64() */
+void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
+{
+ time64_t time64;
+
+ time64 = (time64_t)time;
+ rtc_time_to_tm64(time64, tm);
+}
EXPORT_SYMBOL(rtc_time_to_tm);

/*
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 2a6a9ce..12bacba 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -21,6 +21,7 @@ extern int rtc_year_days(unsigned int day, unsigned int month, unsigned int year
extern int rtc_valid_tm(struct rtc_time *tm);
extern int rtc_tm_to_time64(struct rtc_time *tm, time64_t *time);
extern int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time);
+extern void rtc_time_to_tm64(time64_t time, struct rtc_time *tm);
extern void rtc_time_to_tm(unsigned long time, struct rtc_time *tm);
ktime_t rtc_tm_to_ktime(struct rtc_time tm);
struct rtc_time rtc_ktime_to_tm(ktime_t kt);
--
1.7.9.5


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