NOHZ: prevent multiplication overflow - stop timer for huge timeouts

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

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 3e7ebc4646b7791c798cd148480e1345255cebd9..52db9e3c526e5bba4dc733a6d5ddd77908458401 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -247,6 +247,21 @@ void tick_nohz_stop_sched_tick(void)
                if (cpu == tick_do_timer_cpu)
                        tick_do_timer_cpu = -1;
 
+               ts->idle_sleeps++;
+
+               /*
+                * delta_jiffies >= NEXT_TIMER_MAX_DELTA signals that
+                * there is no timer pending or at least extremly far
+                * into the future (12 days for HZ=1000). In this case
+                * we simply stop the tick timer:
+                */
+               if (unlikely(delta_jiffies >= NEXT_TIMER_MAX_DELTA)) {
+                       ts->idle_expires.tv64 = KTIME_MAX;
+                       if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
+                               hrtimer_cancel(&ts->sched_timer);
+                       goto out;
+               }
+
                /*
                 * calculate the expiry time for the next timer wheel
                 * timer
@@ -254,7 +269,6 @@ void tick_nohz_stop_sched_tick(void)
                expires = ktime_add_ns(last_update, tick_period.tv64 *
                                       delta_jiffies);
                ts->idle_expires = expires;
-               ts->idle_sleeps++;
 
                if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
                        hrtimer_start(&ts->sched_timer, expires,