time: catch xtime_nsec underflows and fix them

[karo-tx-linux.git] / kernel / time / tick-common.c

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index c4777193d56734d0276aa210ddbbad2e79c416c8..bad22e2a552387be455213457ec5d1874f524238 100644 (file)
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -33,7 +33,7 @@ DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
  */
 ktime_t tick_next_period;
 ktime_t tick_period;
-int tick_do_timer_cpu __read_mostly = -1;
+int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
 DEFINE_SPINLOCK(tick_device_lock);
 
 /*
@@ -93,7 +93,17 @@ void tick_handle_periodic(struct clock_event_device *dev)
        for (;;) {
                if (!clockevents_program_event(dev, next, ktime_get()))
                        return;
-               tick_periodic(cpu);
+               /*
+                * Have to be careful here. If we're in oneshot mode,
+                * before we call tick_periodic() in a loop, we need
+                * to be sure we're using a real hardware clocksource.
+                * Otherwise we could get trapped in an infinite
+                * loop, as the tick_periodic() increments jiffies,
+                * when then will increment time, posibly causing
+                * the loop to trigger again and again.
+                */
+               if (timekeeping_valid_for_hres())
+                       tick_periodic(cpu);
                next = ktime_add(next, tick_period);
        }
 }
@@ -109,7 +119,8 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
        if (!tick_device_is_functional(dev))
                return;
 
-       if (dev->features & CLOCK_EVT_FEAT_PERIODIC) {
+       if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
+           !tick_broadcast_oneshot_active()) {
                clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
        } else {
                unsigned long seq;
@@ -148,7 +159,7 @@ static void tick_setup_device(struct tick_device *td,
                 * If no cpu took the do_timer update, assign it to
                 * this cpu:
                 */
-               if (tick_do_timer_cpu == -1) {
+               if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
                        tick_do_timer_cpu = cpu;
                        tick_next_period = ktime_get();
                        tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
@@ -249,7 +260,7 @@ static int tick_check_new_device(struct clock_event_device *newdev)
         * not give it back to the clockevents layer !
         */
        if (tick_is_broadcast_device(curdev)) {
-               clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN);
+               clockevents_shutdown(curdev);
                curdev = NULL;
        }
        clockevents_exchange_device(curdev, newdev);
@@ -300,7 +311,8 @@ static void tick_shutdown(unsigned int *cpup)
        if (*cpup == tick_do_timer_cpu) {
                int cpu = first_cpu(cpu_online_map);
 
-               tick_do_timer_cpu = (cpu != NR_CPUS) ? cpu : -1;
+               tick_do_timer_cpu = (cpu != NR_CPUS) ? cpu :
+                       TICK_DO_TIMER_NONE;
        }
        spin_unlock_irqrestore(&tick_device_lock, flags);
 }
@@ -311,7 +323,7 @@ static void tick_suspend(void)
        unsigned long flags;
 
        spin_lock_irqsave(&tick_device_lock, flags);
-       clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
+       clockevents_shutdown(td->evtdev);
        spin_unlock_irqrestore(&tick_device_lock, flags);
 }