posix-timers: Move interval out of the union

Preparatory patch to unify the alarm timer and hrtimer based posix interval
timer handling.

The interval is used as a criteria for rearming decisions so moving it out
of the clock specific data structures allows later unification.
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/20170530211656.563922908@linutronix.de

include/linux/posix-timers.h

@@ -63,6 +63,7 @@ struct cpu_timer_list {
  * @it_requeue_pending:	Indicator that timer waits for being requeued on
  *			signal delivery
  * @it_sigev_notify:	The notify word of sigevent struct for signal delivery
+ * @it_interval:	The interval for periodic timers
  * @it_signal:		Pointer to the creators signal struct
  * @it_pid:		The pid of the process/task targeted by the signal
  * @it_process:		The task to wakeup on clock_nanosleep (CPU timers)
@@ -80,6 +81,7 @@ struct k_itimer {
 	int			it_overrun_last;
 	int			it_requeue_pending;
 	int			it_sigev_notify;
+	ktime_t			it_interval;
 	struct signal_struct	*it_signal;
 	union {
 		struct pid		*it_pid;
@@ -89,12 +91,10 @@ struct k_itimer {
 	union {
 		struct {
 			struct hrtimer	timer;
-			ktime_t		interval;
 		} real;
 		struct cpu_timer_list	cpu;
 		struct {
 			struct alarm	alarmtimer;
-			ktime_t		interval;
 		} alarm;
 		struct rcu_head		rcu;
 	} it;

kernel/time/alarmtimer.c

@@ -527,9 +527,8 @@ static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 	}
 
 	/* Re-add periodic timers */
-	if (ptr->it.alarm.interval) {
-		ptr->it_overrun += alarm_forward(alarm, now,
-						ptr->it.alarm.interval);
+	if (ptr->it_interval) {
+		ptr->it_overrun += alarm_forward(alarm, now, ptr->it_interval);
 		result = ALARMTIMER_RESTART;
 	}
 	spin_unlock_irqrestore(&ptr->it_lock, flags);
@@ -613,7 +612,7 @@ static void alarm_timer_get(struct k_itimer *timr,
 		cur_setting->it_value.tv_nsec = 0;
 	}
 
-	cur_setting->it_interval = ktime_to_timespec64(timr->it.alarm.interval);
+	cur_setting->it_interval = ktime_to_timespec64(timr->it_interval);
 }
 
 /**
@@ -662,14 +661,14 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
 		return TIMER_RETRY;
 
 	/* start the timer */
-	timr->it.alarm.interval = timespec64_to_ktime(new_setting->it_interval);
+	timr->it_interval = timespec64_to_ktime(new_setting->it_interval);
 
 	/*
 	 * Rate limit to the tick as a hot fix to prevent DOS. Will be
 	 * mopped up later.
 	 */
-	if (timr->it.alarm.interval < TICK_NSEC)
-		timr->it.alarm.interval = TICK_NSEC;
+	if (timr->it_interval < TICK_NSEC)
+		timr->it_interval = TICK_NSEC;
 
 	exp = timespec64_to_ktime(new_setting->it_value);
 	/* Convert (if necessary) to absolute time */

kernel/time/posix-timers.c

@@ -285,12 +285,12 @@ static void schedule_next_timer(struct k_itimer *timr)
 {
 	struct hrtimer *timer = &timr->it.real.timer;
 
-	if (timr->it.real.interval == 0)
+	if (!timr->it_interval)
 		return;
 
 	timr->it_overrun += (unsigned int) hrtimer_forward(timer,
 						timer->base->get_time(),
-						timr->it.real.interval);
+						timr->it_interval);
 	hrtimer_restart(timer);
 }
 
@@ -375,7 +375,7 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
 	timr = container_of(timer, struct k_itimer, it.real.timer);
 	spin_lock_irqsave(&timr->it_lock, flags);
 
-	if (timr->it.real.interval != 0)
+	if (timr->it_interval != 0)
 		si_private = ++timr->it_requeue_pending;
 
 	if (posix_timer_event(timr, si_private)) {
@@ -384,7 +384,7 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
 		 * we will not get a call back to restart it AND
 		 * it should be restarted.
 		 */
-		if (timr->it.real.interval != 0) {
+		if (timr->it_interval != 0) {
 			ktime_t now = hrtimer_cb_get_time(timer);
 
 			/*
@@ -413,13 +413,13 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
 			{
 				ktime_t kj = NSEC_PER_SEC / HZ;
 
-				if (timr->it.real.interval < kj)
+				if (timr->it_interval < kj)
 					now = ktime_add(now, kj);
 			}
 #endif
 			timr->it_overrun += (unsigned int)
 				hrtimer_forward(timer, now,
-						timr->it.real.interval);
+						timr->it_interval);
 			ret = HRTIMER_RESTART;
 			++timr->it_requeue_pending;
 		}
@@ -631,7 +631,7 @@ common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 
 	memset(cur_setting, 0, sizeof(*cur_setting));
 
-	iv = timr->it.real.interval;
+	iv = timr->it_interval;
 
 	/* interval timer ? */
 	if (iv)
@@ -732,7 +732,7 @@ common_timer_set(struct k_itimer *timr, int flags,
 		common_timer_get(timr, old_setting);
 
 	/* disable the timer */
-	timr->it.real.interval = 0;
+	timr->it_interval = 0;
 	/*
 	 * careful here.  If smp we could be in the "fire" routine which will
 	 * be spinning as we hold the lock.  But this is ONLY an SMP issue.
@@ -755,7 +755,7 @@ common_timer_set(struct k_itimer *timr, int flags,
 	hrtimer_set_expires(timer, timespec64_to_ktime(new_setting->it_value));
 
 	/* Convert interval */
-	timr->it.real.interval = timespec64_to_ktime(new_setting->it_interval);
+	timr->it_interval = timespec64_to_ktime(new_setting->it_interval);
 
 	/* SIGEV_NONE timers are not queued ! See common_timer_get */
 	if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
@@ -820,7 +820,7 @@ SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
 
 static int common_timer_del(struct k_itimer *timer)
 {
-	timer->it.real.interval = 0;
+	timer->it_interval = 0;
 
 	if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
 		return TIMER_RETRY;