posix-timers: Use timer_rearm() callback in posixtimer_rearm()

Use the new timer_rearm() callback to replace the conditional hardcoded
calls into the hrtimer and cpu timer code.

This allows later to bring the same logic to alarmtimers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170530211656.889661919@linutronix.de

kernel/time/posix-cpu-timers.c

@@ -15,6 +15,8 @@
 
 #include "posix-timers.h"
 
+static void posix_cpu_timer_rearm(struct k_itimer *timer);
+
 /*
  * Called after updating RLIMIT_CPU to run cpu timer and update
  * tsk->signal->cputime_expires expiration cache if necessary. Needs
@@ -528,7 +530,7 @@ static void cpu_timer_fire(struct k_itimer *timer)
 		 * reload the timer.  But we need to keep it
 		 * ticking in case the signal is deliverable next time.
 		 */
-		posix_cpu_timer_schedule(timer);
+		posix_cpu_timer_rearm(timer);
 		++timer->it_requeue_pending;
 	}
 }
@@ -984,7 +986,7 @@ static void check_process_timers(struct task_struct *tsk,
  * This is called from the signal code (via posixtimer_rearm)
  * when the last timer signal was delivered and we have to reload the timer.
  */
-void posix_cpu_timer_schedule(struct k_itimer *timer)
+static void posix_cpu_timer_rearm(struct k_itimer *timer)
 {
 	struct sighand_struct *sighand;
 	unsigned long flags;
@@ -1431,6 +1433,7 @@ const struct k_clock clock_posix_cpu = {
 	.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 = {

kernel/time/posix-timers.c

@@ -278,10 +278,9 @@ static __init int init_posix_timers(void)
 					NULL);
 	return 0;
 }
-
 __initcall(init_posix_timers);
 
-static void schedule_next_timer(struct k_itimer *timr)
+static void common_hrtimer_rearm(struct k_itimer *timr)
 {
 	struct hrtimer *timer = &timr->it.real.timer;
 
@@ -315,10 +314,7 @@ void posixtimer_rearm(struct siginfo *info)
 		return;
 
 	if (timr->it_requeue_pending == info->si_sys_private) {
-		if (timr->it_clock < 0)
-			posix_cpu_timer_schedule(timr);
-		else
-			schedule_next_timer(timr);
+		timr->kclock->timer_rearm(timr);
 
 		timr->it_overrun_last = timr->it_overrun;
 		timr->it_overrun = -1;
@@ -1046,6 +1042,7 @@ static const struct k_clock clock_realtime = {
 	.timer_set	= common_timer_set,
 	.timer_get	= common_timer_get,
 	.timer_del	= common_timer_del,
+	.timer_rearm	= common_hrtimer_rearm,
 };
 
 static const struct k_clock clock_monotonic = {
@@ -1057,6 +1054,7 @@ static const struct k_clock clock_monotonic = {
 	.timer_set	= common_timer_set,
 	.timer_get	= common_timer_get,
 	.timer_del	= common_timer_del,
+	.timer_rearm	= common_hrtimer_rearm,
 };
 
 static const struct k_clock clock_monotonic_raw = {
@@ -1083,6 +1081,7 @@ static const struct k_clock clock_tai = {
 	.timer_set	= common_timer_set,
 	.timer_get	= common_timer_get,
 	.timer_del	= common_timer_del,
+	.timer_rearm	= common_hrtimer_rearm,
 };
 
 static const struct k_clock clock_boottime = {
@@ -1094,6 +1093,7 @@ static const struct k_clock clock_boottime = {
 	.timer_set	= common_timer_set,
 	.timer_get	= common_timer_get,
 	.timer_del	= common_timer_del,
+	.timer_rearm	= common_hrtimer_rearm,
 };
 
 static const struct k_clock * const posix_clocks[] = {

kernel/time/posix-timers.h

@@ -28,5 +28,3 @@ extern const struct k_clock clock_thread;
 extern const struct k_clock alarm_clock;
 
 int posix_timer_event(struct k_itimer *timr, int si_private);
-
-void posix_cpu_timer_schedule(struct k_itimer *timer);