[PATCHv4 03/28] posix-clocks: add another call back to return clock time in ktime_t

[Dmitry Safonov <dima@arista.com>]

From: Andrei Vagin <avagin@gmail.com>

The callsite in common_timer_get() has already a comment:
        /*
         * The timespec64 based conversion is suboptimal, but it's not
         * worth to implement yet another callback.
         */
        kc->clock_get(timr->it_clock, &ts64);
        now = timespec64_to_ktime(ts64);

Now we are going to add time namespaces and we need to be able to get:
* clock value in a task time namespace to return it from the clock_gettime
  syscall.
* clock valuse in the root time namespace to use it in
  common_timer_get().

It looks like another reason why we need a separate callback to return
clock value in ktime_t.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/posix-timers.h   |  3 ++
 kernel/time/alarmtimer.c       | 24 ++++++++++---
 kernel/time/posix-clock.c      |  8 ++---
 kernel/time/posix-cpu-timers.c | 32 +++++++++---------
 kernel/time/posix-timers.c     | 61 ++++++++++++++++++++++------------
 kernel/time/posix-timers.h     |  7 ++--
 6 files changed, 87 insertions(+), 48 deletions(-)

diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index b20798fc5191..fe13ab265213 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -127,4 +127,7 @@ void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
 
 void posixtimer_rearm(struct kernel_siginfo *info);
+
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp);
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp);
 #endif
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 0519a8805aab..68a163c8b4f2 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -43,6 +43,8 @@ static struct alarm_base {
 	spinlock_t		lock;
 	struct timerqueue_head	timerqueue;
 	ktime_t			(*gettime)(void);
+	int			(*get_timespec)(const clockid_t which_clock,
+						struct timespec64 *tp);
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];
 
@@ -645,21 +647,30 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
 }
 
 /**
- * alarm_clock_get - posix clock_get interface
+ * alarm_clock_get_timespec - posix clock_get_timespec interface
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
  * Provides the underlying alarm base time.
  */
-static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
+static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 
 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;
 
-	*tp = ktime_to_timespec64(base->gettime());
-	return 0;
+	return base->get_timespec(base->base_clockid, tp);
+}
+
+static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
+{
+	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
+
+	if (!alarmtimer_get_rtcdev())
+		return -EINVAL;
+
+	return base->gettime();
 }
 
 /**
@@ -825,7 +836,8 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
 const struct k_clock alarm_clock = {
 	.clock_getres		= alarm_clock_getres,
-	.clock_get		= alarm_clock_get,
+	.clock_get_ktime	= alarm_clock_get_ktime,
+	.clock_get_timespec	= alarm_clock_get_timespec,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_del		= common_timer_del,
@@ -870,8 +882,10 @@ static int __init alarmtimer_init(void)
 	/* Initialize alarm bases */
 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 	alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
+	alarm_bases[ALARM_BOOTTIME].get_timespec = posix_get_timespec,
 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 	alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
+	alarm_bases[ALARM_BOOTTIME].get_timespec = posix_get_boottime_timespec;
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		timerqueue_init_head(&alarm_bases[i].timerqueue);
 		spin_lock_init(&alarm_bases[i].lock);
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index ec960bb939fd..c8f9c9b1cd82 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -315,8 +315,8 @@ static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
 }
 
 const struct k_clock clock_posix_dynamic = {
-	.clock_getres	= pc_clock_getres,
-	.clock_set	= pc_clock_settime,
-	.clock_get	= pc_clock_gettime,
-	.clock_adj	= pc_clock_adjtime,
+	.clock_getres		= pc_clock_getres,
+	.clock_set		= pc_clock_settime,
+	.clock_get_timespec	= pc_clock_gettime,
+	.clock_adj		= pc_clock_adjtime,
 };
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 0a426f4e3125..dccf7dfcd36a 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1417,26 +1417,26 @@ static int thread_cpu_timer_create(struct k_itimer *timer)
 }
 
 const struct k_clock clock_posix_cpu = {
-	.clock_getres	= posix_cpu_clock_getres,
-	.clock_set	= posix_cpu_clock_set,
-	.clock_get	= posix_cpu_clock_get,
-	.timer_create	= posix_cpu_timer_create,
-	.nsleep		= posix_cpu_nsleep,
-	.timer_set	= posix_cpu_timer_set,
-	.timer_del	= posix_cpu_timer_del,
-	.timer_get	= posix_cpu_timer_get,
-	.timer_rearm	= posix_cpu_timer_rearm,
+	.clock_getres		= posix_cpu_clock_getres,
+	.clock_set		= posix_cpu_clock_set,
+	.clock_get_timespec	= posix_cpu_clock_get,
+	.timer_create		= posix_cpu_timer_create,
+	.nsleep			= posix_cpu_nsleep,
+	.timer_set		= posix_cpu_timer_set,
+	.timer_del		= posix_cpu_timer_del,
+	.timer_get		= posix_cpu_timer_get,
+	.timer_rearm		= posix_cpu_timer_rearm,
 };
 
 const struct k_clock clock_process = {
-	.clock_getres	= process_cpu_clock_getres,
-	.clock_get	= process_cpu_clock_get,
-	.timer_create	= process_cpu_timer_create,
-	.nsleep		= process_cpu_nsleep,
+	.clock_getres		= process_cpu_clock_getres,
+	.clock_get_timespec	= process_cpu_clock_get,
+	.timer_create		= process_cpu_timer_create,
+	.nsleep			= process_cpu_nsleep,
 };
 
 const struct k_clock clock_thread = {
-	.clock_getres	= thread_cpu_clock_getres,
-	.clock_get	= thread_cpu_clock_get,
-	.timer_create	= thread_cpu_timer_create,
+	.clock_getres		= thread_cpu_clock_getres,
+	.clock_get_timespec	= thread_cpu_clock_get,
+	.timer_create		= thread_cpu_timer_create,
 };
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 29176635991f..b6fcf6935204 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -165,12 +165,18 @@ static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
 }
 
 /* Get clock_realtime */
-static int posix_clock_realtime_get(clockid_t which_clock, struct timespec64 *tp)
+static int
+posix_clock_realtime_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_real_ts64(tp);
 	return 0;
 }
 
+static ktime_t posix_clock_realtime_get_ktime(clockid_t which_clock)
+{
+	return ktime_get_real();
+}
+
 /* Set clock_realtime */
 static int posix_clock_realtime_set(const clockid_t which_clock,
 				    const struct timespec64 *tp)
@@ -187,12 +193,17 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 /*
  * Get monotonic time for posix timers
  */
-static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
 	return 0;
 }
 
+static ktime_t posix_get_ktime(clockid_t which_clock)
+{
+	return ktime_get();
+}
+
 /*
  * Get monotonic-raw time for posix timers
  */
@@ -222,18 +233,28 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
-static int posix_get_boottime(const clockid_t which_clock, struct timespec64 *tp)
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
 	return 0;
 }
 
-static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
+static ktime_t posix_get_boottime_ktime(const clockid_t which_clock)
+{
+	return ktime_get_boottime();
+}
+
+static int posix_get_tai_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_clocktai_ts64(tp);
 	return 0;
 }
 
+static ktime_t posix_get_tai_ktime(clockid_t which_clock)
+{
+	return ktime_get_clocktai();
+}
+
 static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
 {
 	tp->tv_sec = 0;
@@ -645,7 +666,6 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 {
 	const struct k_clock *kc = timr->kclock;
 	ktime_t now, remaining, iv;
-	struct timespec64 ts64;
 	bool sig_none;
 
 	sig_none = timr->it_sigev_notify == SIGEV_NONE;
@@ -663,12 +683,7 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 			return;
 	}
 
-	/*
-	 * The timespec64 based conversion is suboptimal, but it's not
-	 * worth to implement yet another callback.
-	 */
-	kc->clock_get(timr->it_clock, &ts64);
-	now = timespec64_to_ktime(ts64);
+	now = kc->clock_get_ktime(timr->it_clock);
 
 	/*
 	 * When a requeue is pending or this is a SIGEV_NONE timer move the
@@ -781,7 +796,7 @@ static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
 	 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
 	 * clock modifications, so they become CLOCK_MONOTONIC based under the
 	 * hood. See hrtimer_init(). Update timr->kclock, so the generic
-	 * functions which use timr->kclock->clock_get() work.
+	 * functions which use timr->kclock->clock_get_*() work.
 	 *
 	 * Note: it_clock stays unmodified, because the next timer_set() might
 	 * use ABSTIME, so it needs to switch back.
@@ -1039,7 +1054,7 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 	if (!kc)
 		return -EINVAL;
 
-	error = kc->clock_get(which_clock, &kernel_tp);
+	error = kc->clock_get_timespec(which_clock, &kernel_tp);
 
 	if (!error && put_timespec64(&kernel_tp, tp))
 		error = -EFAULT;
@@ -1121,7 +1136,7 @@ SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
 	if (!kc)
 		return -EINVAL;
 
-	err = kc->clock_get(which_clock, &ts);
+	err = kc->clock_get_timespec(which_clock, &ts);
 
 	if (!err && put_old_timespec32(&ts, tp))
 		err = -EFAULT;
@@ -1233,7 +1248,8 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 
 static const struct k_clock clock_realtime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_clock_realtime_get,
+	.clock_get_timespec	= posix_clock_realtime_get_timespec,
+	.clock_get_ktime	= posix_clock_realtime_get_ktime,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1250,7 +1266,8 @@ static const struct k_clock clock_realtime = {
 
 static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_ktime_get_ts,
+	.clock_get_timespec	= posix_get_timespec,
+	.clock_get_ktime	= posix_get_ktime,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1265,22 +1282,23 @@ static const struct k_clock clock_monotonic = {
 
 static const struct k_clock clock_monotonic_raw = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_monotonic_raw,
+	.clock_get_timespec	= posix_get_monotonic_raw,
 };
 
 static const struct k_clock clock_realtime_coarse = {
 	.clock_getres		= posix_get_coarse_res,
-	.clock_get		= posix_get_realtime_coarse,
+	.clock_get_timespec	= posix_get_realtime_coarse,
 };
 
 static const struct k_clock clock_monotonic_coarse = {
 	.clock_getres		= posix_get_coarse_res,
-	.clock_get		= posix_get_monotonic_coarse,
+	.clock_get_timespec	= posix_get_monotonic_coarse,
 };
 
 static const struct k_clock clock_tai = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_tai,
+	.clock_get_ktime	= posix_get_tai_ktime,
+	.clock_get_timespec	= posix_get_tai_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1295,7 +1313,8 @@ static const struct k_clock clock_tai = {
 
 static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_boottime,
+	.clock_get_ktime	= posix_get_boottime_ktime,
+	.clock_get_timespec	= posix_get_boottime_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
index de5daa6d975a..ff227cd1bdbb 100644
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -6,8 +6,11 @@ struct k_clock {
 				struct timespec64 *tp);
 	int	(*clock_set)(const clockid_t which_clock,
 			     const struct timespec64 *tp);
-	int	(*clock_get)(const clockid_t which_clock,
-			     struct timespec64 *tp);
+	/* return the clock value in the current time namespace. */
+	int	(*clock_get_timespec)(const clockid_t which_clock,
+				      struct timespec64 *tp);
+	/* return the clock value in the root time namespace. */
+	ktime_t	(*clock_get_ktime)(const clockid_t which_clock);
 	int	(*clock_adj)(const clockid_t which_clock, struct __kernel_timex *tx);
 	int	(*timer_create)(struct k_itimer *timer);
 	int	(*nsleep)(const clockid_t which_clock, int flags,
-- 
2.22.0