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Subject[PATCH 04/12] time: Provide y2038 safe do_settimeofday() replacement
Date
From: "pang.xunlei" <pang.xunlei@linaro.org>

The kernel uses 32-bit signed value(time_t) for seconds elapsed
1970-01-01:00:00:00, thus it will overflow at 2038-01-19 03:14:08
on 32-bit systems. This is widely known as the y2038 problem.

As part of addressing "y2038 problem" for in-kernel uses, this patch
adds safe do_settimeofday64() using timespec64.

After this patch, do_settimeofday() is deprecated and all its call
sites will be fixed using do_settimeofday64(), after that it can be
removed.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnd Bergmann <arnd.bergmann@linaro.org>
Cc: pang.xunlei <pang.xunlei@linaro.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
include/linux/timekeeping.h | 21 ++++++++++++++++++++-
kernel/time/timekeeping.c | 19 +++++++++----------
2 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 1caa6b0..071ad7e 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -10,7 +10,7 @@ extern int timekeeping_suspended;
* Get and set timeofday
*/
extern void do_gettimeofday(struct timeval *tv);
-extern int do_settimeofday(const struct timespec *tv);
+extern int do_settimeofday64(const struct timespec64 *ts);
extern int do_sys_settimeofday(const struct timespec *tv,
const struct timezone *tz);

@@ -33,6 +33,14 @@ extern int __getnstimeofday64(struct timespec64 *tv);
extern void getnstimeofday64(struct timespec64 *tv);

#if BITS_PER_LONG == 64
+/**
+ * Deprecated. Use do_settimeofday64().
+ */
+static inline int do_settimeofday(const struct timespec *ts)
+{
+ return do_settimeofday64(ts);
+}
+
static inline int __getnstimeofday(struct timespec *ts)
{
return __getnstimeofday64(ts);
@@ -54,6 +62,17 @@ static inline void ktime_get_real_ts(struct timespec *ts)
}

#else
+/**
+ * Deprecated. Use do_settimeofday64().
+ */
+static inline int do_settimeofday(const struct timespec *ts)
+{
+ struct timespec64 ts64;
+
+ ts64 = timespec_to_timespec64(*ts);
+ return do_settimeofday64(&ts64);
+}
+
static inline int __getnstimeofday(struct timespec *ts)
{
struct timespec64 ts64;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index ec1791f..1d33550 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -703,18 +703,18 @@ void do_gettimeofday(struct timeval *tv)
EXPORT_SYMBOL(do_gettimeofday);

/**
- * do_settimeofday - Sets the time of day
- * @tv: pointer to the timespec variable containing the new time
+ * do_settimeofday64 - Sets the time of day.
+ * @ts: pointer to the timespec64 variable containing the new time
*
* Sets the time of day to the new time and update NTP and notify hrtimers
*/
-int do_settimeofday(const struct timespec *tv)
+int do_settimeofday64(const struct timespec64 *ts)
{
struct timekeeper *tk = &tk_core.timekeeper;
- struct timespec64 ts_delta, xt, tmp;
+ struct timespec64 ts_delta, xt;
unsigned long flags;

- if (!timespec_valid_strict(tv))
+ if (!timespec64_valid_strict(ts))
return -EINVAL;

raw_spin_lock_irqsave(&timekeeper_lock, flags);
@@ -723,13 +723,12 @@ int do_settimeofday(const struct timespec *tv)
timekeeping_forward_now(tk);

xt = tk_xtime(tk);
- ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
- ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
+ ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
+ ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;

tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));

- tmp = timespec_to_timespec64(*tv);
- tk_set_xtime(tk, &tmp);
+ tk_set_xtime(tk, ts);

timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);

@@ -741,7 +740,7 @@ int do_settimeofday(const struct timespec *tv)

return 0;
}
-EXPORT_SYMBOL(do_settimeofday);
+EXPORT_SYMBOL(do_settimeofday64);

/**
* timekeeping_inject_offset - Adds or subtracts from the current time.
--
1.9.1


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