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Subject[tip:timers/core] timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock
Commit-ID:  72199320d49dbafa1a99f94f1cd60dc90035c154
Gitweb: https://git.kernel.org/tip/72199320d49dbafa1a99f94f1cd60dc90035c154
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Thu, 1 Mar 2018 17:33:32 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 13 Mar 2018 07:34:21 +0100

timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock

The planned change to unify the behaviour of the MONOTONIC and BOOTTIME
clocks vs. suspend removes the ability to retrieve the active
non-suspended time of a system.

Provide a new CLOCK_MONOTONIC_ACTIVE clock which returns the active
non-suspended time of the system via clock_gettime().

This preserves the old behaviour of CLOCK_MONOTONIC before the
BOOTTIME/MONOTONIC unification.

This new clock also allows applications to detect programmatically that
the MONOTONIC and BOOTTIME clocks are identical.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20180301165149.965235774@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/timekeeper_internal.h | 2 ++
include/linux/timekeeping.h | 1 +
include/uapi/linux/time.h | 1 +
kernel/time/posix-stubs.c | 2 ++
kernel/time/posix-timers.c | 13 +++++++++++++
kernel/time/timekeeping.c | 36 ++++++++++++++++++++++++++++++++++++
6 files changed, 55 insertions(+)

diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h
index 7acb953298a7..4b3dca173e89 100644
--- a/include/linux/timekeeper_internal.h
+++ b/include/linux/timekeeper_internal.h
@@ -52,6 +52,7 @@ struct tk_read_base {
* @offs_real: Offset clock monotonic -> clock realtime
* @offs_boot: Offset clock monotonic -> clock boottime
* @offs_tai: Offset clock monotonic -> clock tai
+ * @time_suspended: Accumulated suspend time
* @tai_offset: The current UTC to TAI offset in seconds
* @clock_was_set_seq: The sequence number of clock was set events
* @cs_was_changed_seq: The sequence number of clocksource change events
@@ -94,6 +95,7 @@ struct timekeeper {
ktime_t offs_real;
ktime_t offs_boot;
ktime_t offs_tai;
+ ktime_t time_suspended;
s32 tai_offset;
unsigned int clock_was_set_seq;
u8 cs_was_changed_seq;
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index b17bcce58bc4..440b1935d3a5 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -32,6 +32,7 @@ extern void getrawmonotonic64(struct timespec64 *ts);
extern void ktime_get_ts64(struct timespec64 *ts);
extern time64_t ktime_get_seconds(void);
extern time64_t ktime_get_real_seconds(void);
+extern void ktime_get_active_ts64(struct timespec64 *ts);

extern int __getnstimeofday64(struct timespec64 *tv);
extern void getnstimeofday64(struct timespec64 *tv);
diff --git a/include/uapi/linux/time.h b/include/uapi/linux/time.h
index 53f8dd84beb5..61a187df8da2 100644
--- a/include/uapi/linux/time.h
+++ b/include/uapi/linux/time.h
@@ -61,6 +61,7 @@ struct itimerval {
*/
#define CLOCK_SGI_CYCLE 10
#define CLOCK_TAI 11
+#define CLOCK_MONOTONIC_ACTIVE 12

#define MAX_CLOCKS 16
#define CLOCKS_MASK (CLOCK_REALTIME | CLOCK_MONOTONIC)
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index b258bee13b02..6259dbc0191a 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -73,6 +73,8 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
case CLOCK_BOOTTIME:
get_monotonic_boottime64(tp);
break;
+ case CLOCK_MONOTONIC_ACTIVE:
+ ktime_get_active_ts64(tp);
default:
return -EINVAL;
}
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 75043046914e..556fe02a47a4 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -263,6 +263,13 @@ static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
return 0;
}

+static int posix_get_monotonic_active(clockid_t which_clock,
+ struct timespec64 *tp)
+{
+ ktime_get_active_ts64(tp);
+ return 0;
+}
+
static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
{
tp->tv_sec = 0;
@@ -1330,6 +1337,11 @@ static const struct k_clock clock_boottime = {
.timer_arm = common_hrtimer_arm,
};

+static const struct k_clock clock_monotonic_active = {
+ .clock_getres = posix_get_hrtimer_res,
+ .clock_get = posix_get_monotonic_active,
+};
+
static const struct k_clock * const posix_clocks[] = {
[CLOCK_REALTIME] = &clock_realtime,
[CLOCK_MONOTONIC] = &clock_monotonic,
@@ -1342,6 +1354,7 @@ static const struct k_clock * const posix_clocks[] = {
[CLOCK_REALTIME_ALARM] = &alarm_clock,
[CLOCK_BOOTTIME_ALARM] = &alarm_clock,
[CLOCK_TAI] = &clock_tai,
+ [CLOCK_MONOTONIC_ACTIVE] = &clock_monotonic_active,
};

static const struct k_clock *clockid_to_kclock(const clockid_t id)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e11760121cb2..a2b7f583e64e 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -139,6 +139,9 @@ static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
{
tk->offs_boot = ktime_add(tk->offs_boot, delta);
+
+ /* Accumulate time spent in suspend */
+ tk->time_suspended += delta;
}

/*
@@ -886,6 +889,39 @@ void ktime_get_ts64(struct timespec64 *ts)
}
EXPORT_SYMBOL_GPL(ktime_get_ts64);

+/**
+ * ktime_get_active_ts64 - Get the active non-suspended monotonic clock
+ * @ts: pointer to timespec variable
+ *
+ * The function calculates the monotonic clock from the realtime clock and
+ * the wall_to_monotonic offset, subtracts the accumulated suspend time and
+ * stores the result in normalized timespec64 format in the variable
+ * pointed to by @ts.
+ */
+void ktime_get_active_ts64(struct timespec64 *ts)
+{
+ struct timekeeper *tk = &tk_core.timekeeper;
+ struct timespec64 tomono, tsusp;
+ u64 nsec, nssusp;
+ unsigned int seq;
+
+ WARN_ON(timekeeping_suspended);
+
+ do {
+ seq = read_seqcount_begin(&tk_core.seq);
+ ts->tv_sec = tk->xtime_sec;
+ nsec = timekeeping_get_ns(&tk->tkr_mono);
+ tomono = tk->wall_to_monotonic;
+ nssusp = tk->time_suspended;
+ } while (read_seqcount_retry(&tk_core.seq, seq));
+
+ ts->tv_sec += tomono.tv_sec;
+ ts->tv_nsec = 0;
+ timespec64_add_ns(ts, nsec + tomono.tv_nsec);
+ tsusp = ns_to_timespec64(nssusp);
+ *ts = timespec64_sub(*ts, tsusp);
+}
+
/**
* ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
*
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