[patch 05/48] hrtimer: Avoid pointless reprogramming in __hrtimer_start_range_ns()

[Thomas Gleixner <tglx@kernel.org>]

From: Peter Zijlstra <peterz@infradead.org>

Much like hrtimer_reprogram(), skip programming if the cpu_base is running
the hrtimer interrupt.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@kernel.org>
---
 kernel/time/hrtimer.c |    8 ++++++++
 1 file changed, 8 insertions(+)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1269,6 +1269,14 @@ static int __hrtimer_start_range_ns(stru
 	}
 
 	first = enqueue_hrtimer(timer, new_base, mode);
+
+	/*
+	 * If the hrtimer interrupt is running, then it will reevaluate the
+	 * clock bases and reprogram the clock event device.
+	 */
+	if (new_base->cpu_base->in_hrtirq)
+		return false;
+
 	if (!force_local) {
 		/*
 		 * If the current CPU base is online, then the timer is