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timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock

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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>
This commit is contained in:
Thomas Gleixner 2018-03-01 17:33:32 +01:00 committed by Ingo Molnar
parent 78b98e3c5a
commit 72199320d4
6 changed files with 55 additions and 0 deletions
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2
include/linux/timekeeper_internal.h
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@ -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;

1
include/linux/timekeeping.h
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@ -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);

1
include/uapi/linux/time.h
View File

@ -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)

2
kernel/time/posix-stubs.c
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@ -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;
}

13
kernel/time/posix-timers.c
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@ -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)

36
kernel/time/timekeeping.c
View File

@ -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
*