[PATCH 02/21] time: Add y2038 safe read_persistent_clock64()

John Stultz
2015-04-02T03:39:34Z

From: Xunlei Pang <pang.xunlei@linaro.org>

As part of addressing in-kernel y2038 issues, this patch adds
read_persistent_clock64() and replaces all the call sites of
read_persistent_clock() with this function. This is a __weak
implementation, which simply calls the existing y2038 unsafe
read_persistent_clock().

This allows architecture specific implementations to be converted
independently, and eventually the y2038 unsafe read_persistent_clock()
can be removed after all its architecture specific implementations
have been converted to read_persistent_clock64().

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
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>
---
arch/mips/lasat/sysctl.c | 4 ++--
include/linux/timekeeping.h | 1 +
kernel/time/timekeeping.c | 22 ++++++++++++----------
3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/arch/mips/lasat/sysctl.c b/arch/mips/lasat/sysctl.c
index 3b7f65c..cf9b4633 100644
--- a/arch/mips/lasat/sysctl.c
+++ b/arch/mips/lasat/sysctl.c
@@ -75,11 +75,11 @@ static int rtctmp;
int proc_dolasatrtc(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
- struct timespec ts;
+ struct timespec64 ts;
int r;

if (!write) {
- read_persistent_clock(&ts);
+ read_persistent_clock64(&ts);
rtctmp = ts.tv_sec;
/* check for time < 0 and set to 0 */
if (rtctmp < 0)
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 18d27a3..4c0f76f 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -268,6 +268,7 @@ static inline bool has_persistent_clock(void)
}

extern void read_persistent_clock(struct timespec *ts);
+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);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 50c4bec..39df498 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1173,6 +1173,14 @@ void __weak read_persistent_clock(struct timespec *ts)
ts->tv_nsec = 0;
}

+void __weak read_persistent_clock64(struct timespec64 *ts64)
+{
+ struct timespec ts;
+
+ read_persistent_clock(&ts);
+ *ts64 = timespec_to_timespec64(ts);
+}
+
/**
* read_boot_clock - Return time of the system start.
*
@@ -1205,10 +1213,8 @@ void __init timekeeping_init(void)
struct clocksource *clock;
unsigned long flags;
struct timespec64 now, boot, tmp;
- struct timespec ts;

- read_persistent_clock(&ts);
- now = timespec_to_timespec64(ts);
+ read_persistent_clock64(&now);
if (!timespec64_valid_strict(&now)) {
pr_warn("WARNING: Persistent clock returned invalid value!\n"
" Check your CMOS/BIOS settings.\n");
@@ -1278,7 +1284,7 @@ static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
* timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
* @delta: pointer to a timespec64 delta value
*
- * This hook is for architectures that cannot support read_persistent_clock
+ * This hook is for architectures that cannot support read_persistent_clock64
* because their RTC/persistent clock is only accessible when irqs are enabled.
*
* This function should only be called by rtc_resume(), and allows
@@ -1325,12 +1331,10 @@ void timekeeping_resume(void)
struct clocksource *clock = tk->tkr_mono.clock;
unsigned long flags;
struct timespec64 ts_new, ts_delta;
- struct timespec tmp;
cycle_t cycle_now, cycle_delta;
bool suspendtime_found = false;

- read_persistent_clock(&tmp);
- ts_new = timespec_to_timespec64(tmp);
+ read_persistent_clock64(&ts_new);

clockevents_resume();
clocksource_resume();
@@ -1408,10 +1412,8 @@ int timekeeping_suspend(void)
unsigned long flags;
struct timespec64 delta, delta_delta;
static struct timespec64 old_delta;
- struct timespec tmp;

- read_persistent_clock(&tmp);
- timekeeping_suspend_time = timespec_to_timespec64(tmp);
+ read_persistent_clock64(&timekeeping_suspend_time);

/*
* On some systems the persistent_clock can not be detected at
--
1.9.1