[PATCH 4/6] time: Add time64_to_tm()

From: John Stultz
Date: Mon Jun 20 2016 - 15:57:04 EST


From: Deepa Dinamani <deepa.kernel@xxxxxxxxx>

time_to_tm() takes time_t as an argument.
time_t is not y2038 safe.
Add time64_to_tm() that takes time64_t as an argument
which is y2038 safe.
The plan is to eventually replace all calls to time_to_tm()
by time64_to_tm().

Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Deepa Dinamani <deepa.kernel@xxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
include/linux/time.h | 15 ++++++++++++++-
kernel/time/timeconv.c | 11 ++++++-----
2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/include/linux/time.h b/include/linux/time.h
index 297f09f..4cea09d 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -205,7 +205,20 @@ struct tm {
int tm_yday;
};

-void time_to_tm(time_t totalsecs, int offset, struct tm *result);
+void time64_to_tm(time64_t totalsecs, int offset, struct tm *result);
+
+/**
+ * time_to_tm - converts the calendar time to local broken-down time
+ *
+ * @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970,
+ * Coordinated Universal Time (UTC).
+ * @offset offset seconds adding to totalsecs.
+ * @result pointer to struct tm variable to receive broken-down time
+ */
+static inline void time_to_tm(time_t totalsecs, int offset, struct tm *result)
+{
+ time64_to_tm(totalsecs, offset, result);
+}

/**
* timespec_to_ns - Convert timespec to nanoseconds
diff --git a/kernel/time/timeconv.c b/kernel/time/timeconv.c
index 86628e7..7142580 100644
--- a/kernel/time/timeconv.c
+++ b/kernel/time/timeconv.c
@@ -67,20 +67,21 @@ static const unsigned short __mon_yday[2][13] = {
#define SECS_PER_DAY (SECS_PER_HOUR * 24)

/**
- * time_to_tm - converts the calendar time to local broken-down time
+ * time64_to_tm - converts the calendar time to local broken-down time
*
* @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970,
* Coordinated Universal Time (UTC).
* @offset offset seconds adding to totalsecs.
* @result pointer to struct tm variable to receive broken-down time
*/
-void time_to_tm(time_t totalsecs, int offset, struct tm *result)
+void time64_to_tm(time64_t totalsecs, int offset, struct tm *result)
{
long days, rem, y;
+ int remainder;
const unsigned short *ip;

- days = totalsecs / SECS_PER_DAY;
- rem = totalsecs % SECS_PER_DAY;
+ days = div_s64_rem(totalsecs, SECS_PER_DAY, &remainder);
+ rem = remainder;
rem += offset;
while (rem < 0) {
rem += SECS_PER_DAY;
@@ -124,4 +125,4 @@ void time_to_tm(time_t totalsecs, int offset, struct tm *result)
result->tm_mon = y;
result->tm_mday = days + 1;
}
-EXPORT_SYMBOL(time_to_tm);
+EXPORT_SYMBOL(time64_to_tm);
--
1.9.1