time: Introduce struct itimerspec64

The struct itimerspec is not year 2038 safe on 32bit systems due to
the limitation of the struct timespec members. Introduce itimerspec64
which uses struct timespec64 instead and provide conversion functions.

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

include/linux/time64.h

@@ -12,11 +12,18 @@ typedef __s64 time64_t;
  */
 #if __BITS_PER_LONG == 64
 # define timespec64 timespec
+#define itimerspec64 itimerspec
 #else
 struct timespec64 {
 	time64_t	tv_sec;			/* seconds */
 	long		tv_nsec;		/* nanoseconds */
 };
+
+struct itimerspec64 {
+	struct timespec64 it_interval;
+	struct timespec64 it_value;
+};
+
 #endif
 
 /* Parameters used to convert the timespec values: */
@@ -45,6 +52,16 @@ static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
 	return ts;
 }
 
+static inline struct itimerspec itimerspec64_to_itimerspec(struct itimerspec64 *its64)
+{
+	return *its64;
+}
+
+static inline struct itimerspec64 itimerspec_to_itimerspec64(struct itimerspec *its)
+{
+	return *its;
+}
+
 # define timespec64_equal		timespec_equal
 # define timespec64_compare		timespec_compare
 # define set_normalized_timespec64	set_normalized_timespec
@@ -77,6 +94,24 @@ static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
 	return ret;
 }
 
+static inline struct itimerspec itimerspec64_to_itimerspec(struct itimerspec64 *its64)
+{
+	struct itimerspec ret;
+
+	ret.it_interval = timespec64_to_timespec(its64->it_interval);
+	ret.it_value = timespec64_to_timespec(its64->it_value);
+	return ret;
+}
+
+static inline struct itimerspec64 itimerspec_to_itimerspec64(struct itimerspec *its)
+{
+	struct itimerspec64 ret;
+
+	ret.it_interval = timespec_to_timespec64(its->it_interval);
+	ret.it_value = timespec_to_timespec64(its->it_value);
+	return ret;
+}
+
 static inline int timespec64_equal(const struct timespec64 *a,
 				   const struct timespec64 *b)
 {