posix-clocks: Rename the clock_get() callback to clock_get_timespec()

The upcoming support for time namespaces requires to have access to:

 - The time in a task's time namespace for sys_clock_gettime()
 - The time in the root name space for common_timer_get()

That adds a valid reason to finally implement a separate callback which
returns the time in ktime_t format, rather than in (struct timespec).

Rename the clock_get() callback to clock_get_timespec() as a preparation
for introducing clock_get_ktime().
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-6-dima@arista.com

kernel/time/alarmtimer.c

@@ -657,7 +657,7 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
 }
 
 /**
- * alarm_clock_get - posix clock_get interface
+ * alarm_clock_get - posix clock_get_timespec interface
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
@@ -837,7 +837,7 @@ 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_timespec	= alarm_clock_get,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_del		= common_timer_del,

kernel/time/posix-clock.c

@@ -310,8 +310,8 @@ 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,
 };

kernel/time/posix-cpu-timers.c

@@ -1391,26 +1391,26 @@ 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,
 };

kernel/time/posix-timers.c

@@ -667,7 +667,7 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 	 * The timespec64 based conversion is suboptimal, but it's not
 	 * worth to implement yet another callback.
 	 */
-	kc->clock_get(timr->it_clock, &ts64);
+	kc->clock_get_timespec(timr->it_clock, &ts64);
 	now = timespec64_to_ktime(ts64);
 
 	/*
@@ -781,7 +781,7 @@ 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_timespec() work.
 	 *
 	 * Note: it_clock stays unmodified, because the next timer_set() might
 	 * use ABSTIME, so it needs to switch back.
@@ -1067,7 +1067,7 @@ 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;
@@ -1149,7 +1149,7 @@ 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;
@@ -1261,7 +1261,7 @@ 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,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1279,7 +1279,7 @@ 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_ktime_get_ts,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1295,22 +1295,22 @@ 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_timespec	= posix_get_tai,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1326,7 +1326,7 @@ 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_timespec	= posix_get_boottime,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,

kernel/time/posix-timers.h

@@ -6,8 +6,8 @@ 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);
+	int	(*clock_get_timespec)(const clockid_t which_clock,
+				      struct timespec64 *tp);
 	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,