time: Add y2038 safe update_persistent_clock64()

As part of addressing in-kernel y2038 issues, this patch adds
update_persistent_clock64() and replaces all the call sites of
update_persistent_clock() with this function. This is a __weak
implementation, which simply calls the existing y2038 unsafe
update_persistent_clock().

This allows architecture specific implementations to be
converted independently, and eventually y2038-unsafe
update_persistent_clock() can be removed after all its
architecture specific implementations have been converted to
update_persistent_clock64().

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 14 insertions, 2 deletions

diff --git a/drivers/rtc/systohc.c b/drivers/rtc/systohc.c
index eb71872d0361..ef3c07a52c3a 100644
--- a/drivers/rtc/systohc.c
+++ b/drivers/rtc/systohc.c
@@ -11,7 +11,7 @@
  * rtc_set_ntp_time - Save NTP synchronized time to the RTC
  * @now: Current time of day
  *
- * Replacement for the NTP platform function update_persistent_clock
+ * Replacement for the NTP platform function update_persistent_clock64
  * that stores time for later retrieval by rtc_hctosys.
  *
  * Returns 0 on successful RTC update, -ENODEV if a RTC update is not
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 4c0f76f4616c..7a2369d5b3f4 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -272,6 +272,7 @@ extern void read_persistent_clock64(struct timespec64 *ts);
 extern void read_boot_clock(struct timespec *ts);
 extern void read_boot_clock64(struct timespec64 *ts);
 extern int update_persistent_clock(struct timespec now);
+extern int update_persistent_clock64(struct timespec64 now);
 
 
 #endif
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 9ad60d028508..7a681003001c 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -458,6 +458,16 @@ out:
         return leap;
 }
 
+#ifdef CONFIG_GENERIC_CMOS_UPDATE
+int __weak update_persistent_clock64(struct timespec64 now64)
+{
+        struct timespec now;
+
+        now = timespec64_to_timespec(now64);
+        return update_persistent_clock(now);
+}
+#endif
+
 #if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
 static void sync_cmos_clock(struct work_struct *work);
 
@@ -493,8 +503,9 @@ static void sync_cmos_clock(struct work_struct *work)
                 if (persistent_clock_is_local)
                         adjust.tv_sec -= (sys_tz.tz_minuteswest * 60);
 #ifdef CONFIG_GENERIC_CMOS_UPDATE
-                fail = update_persistent_clock(timespec64_to_timespec(adjust));
+                fail = update_persistent_clock64(adjust);
 #endif
+
 #ifdef CONFIG_RTC_SYSTOHC
                 if (fail == -ENODEV)
                         fail = rtc_set_ntp_time(adjust);