1 files changed, 30 insertions, 2 deletions

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 99578f06c8d4..f7cc7abfcf25 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -650,6 +650,11 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
         ts->next_tick = 0;
 }
 
+static inline bool local_timer_softirq_pending(void)
+{
+        return local_softirq_pending() & TIMER_SOFTIRQ;
+}
+
 static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
                                          ktime_t now, int cpu)
 {
@@ -666,8 +671,18 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
         } while (read_seqretry(&jiffies_lock, seq));
         ts->last_jiffies = basejiff;
 
-        if (rcu_needs_cpu(basemono, &next_rcu) ||
-            arch_needs_cpu() || irq_work_needs_cpu()) {
+        /*
+         * Keep the periodic tick, when RCU, architecture or irq_work
+         * requests it.
+         * Aside of that check whether the local timer softirq is
+         * pending. If so its a bad idea to call get_next_timer_interrupt()
+         * because there is an already expired timer, so it will request
+         * immeditate expiry, which rearms the hardware timer with a
+         * minimal delta which brings us back to this place
+         * immediately. Lather, rinse and repeat...
+         */
+        if (rcu_needs_cpu(basemono, &next_rcu) || arch_needs_cpu() ||
+            irq_work_needs_cpu() || local_timer_softirq_pending()) {
                 next_tick = basemono + TICK_NSEC;
         } else {
                 /*
@@ -986,6 +1001,19 @@ ktime_t tick_nohz_get_sleep_length(void)
 }
 
 /**
+ * tick_nohz_get_idle_calls_cpu - return the current idle calls counter value
+ * for a particular CPU.
+ *
+ * Called from the schedutil frequency scaling governor in scheduler context.
+ */
+unsigned long tick_nohz_get_idle_calls_cpu(int cpu)
+{
+        struct tick_sched *ts = tick_get_tick_sched(cpu);
+
+        return ts->idle_calls;
+}
+
+/**
  * tick_nohz_get_idle_calls - return the current idle calls counter value
  *
  * Called from the schedutil frequency scaling governor in scheduler context.