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Subject[tip:timers/clocksource] time: Implement timespec_add
Commit-ID:  ce3bf7ab22527183634a76512d9854a38615e4d5
Gitweb: http://git.kernel.org/tip/ce3bf7ab22527183634a76512d9854a38615e4d5
Author: John Stultz <johnstul@us.ibm.com>
AuthorDate: Tue, 13 Jul 2010 17:56:19 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 27 Jul 2010 12:40:53 +0200

time: Implement timespec_add

After accidentally misusing timespec_add_safe, I wanted to make sure
we don't accidently trip over that issue again, so I created a simple
timespec_add() function which we can use to replace the instances
of timespec_add_safe() that don't want the overflow detection.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-3-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
include/linux/time.h | 16 ++++++++++++++++
kernel/time/timekeeping.c | 6 +++---
2 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/include/linux/time.h b/include/linux/time.h
index ea3559f0..9072df8 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -76,9 +76,25 @@ extern unsigned long mktime(const unsigned int year, const unsigned int mon,
const unsigned int min, const unsigned int sec);

extern void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec);
+
+/*
+ * timespec_add_safe assumes both values are positive and checks
+ * for overflow. It will return TIME_T_MAX if the reutrn would be
+ * smaller then either of the arguments.
+ */
extern struct timespec timespec_add_safe(const struct timespec lhs,
const struct timespec rhs);

+
+static inline struct timespec timespec_add(struct timespec lhs,
+ struct timespec rhs)
+{
+ struct timespec ts_delta;
+ set_normalized_timespec(&ts_delta, lhs.tv_sec + rhs.tv_sec,
+ lhs.tv_nsec + rhs.tv_nsec);
+ return ts_delta;
+}
+
/*
* sub = lhs - rhs, in normalized form
*/
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index caf8d4d..623fe3d 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -579,9 +579,9 @@ static int timekeeping_resume(struct sys_device *dev)

if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
ts = timespec_sub(ts, timekeeping_suspend_time);
- xtime = timespec_add_safe(xtime, ts);
+ xtime = timespec_add(xtime, ts);
wall_to_monotonic = timespec_sub(wall_to_monotonic, ts);
- total_sleep_time = timespec_add_safe(total_sleep_time, ts);
+ total_sleep_time = timespec_add(total_sleep_time, ts);
}
/* re-base the last cycle value */
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
@@ -887,7 +887,7 @@ EXPORT_SYMBOL_GPL(getboottime);
*/
void monotonic_to_bootbased(struct timespec *ts)
{
- *ts = timespec_add_safe(*ts, total_sleep_time);
+ *ts = timespec_add(*ts, total_sleep_time);
}
EXPORT_SYMBOL_GPL(monotonic_to_bootbased);


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