patches/softirq-wake-the-timer-softirq-if-needed.patch

From: Mike Galbraith <efault@gmx.de>
Date: Fri, 20 Jan 2017 18:10:20 +0100
Subject: [PATCH] softirq: wake the timer softirq if needed

The irq-exit path only checks the "normal"-softirq thread if it is
running and ignores the state of the "timer"-softirq thread. It is possible
that the timer-softirq thread is and has work pending which leads to the
following warning:

[   84.087571] NOHZ: local_softirq_pending 02
[   84.087593] NOHZ: local_softirq_pending 02
[   84.087598] NOHZ: local_softirq_pending 02
[   84.087904] NOHZ: local_softirq_pending 02
[   84.088526] NOHZ: local_softirq_pending 02
[   84.088899] NOHZ: local_softirq_pending 02
[   84.089463] NOHZ: local_softirq_pending 02
[  115.013470] NOHZ: local_softirq_pending 02
[  115.013601] NOHZ: local_softirq_pending 02
[  115.013709] NOHZ: local_softirq_pending 02

This was introduced during the timer-softirq split.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/softirq.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -28,6 +28,7 @@
 #include <linux/tick.h>
 #include <linux/locallock.h>
 #include <linux/irq.h>
+#include <linux/sched/types.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/irq.h>
@@ -206,6 +207,7 @@ static void handle_softirq(unsigned int
 	}
 }
 
+#ifndef CONFIG_PREEMPT_RT_FULL
 /*
  * If ksoftirqd is scheduled, we do not want to process pending softirqs
  * right now. Let ksoftirqd handle this at its own rate, to get fairness.
@@ -217,7 +219,6 @@ static bool ksoftirqd_running(void)
 	return tsk && (tsk->state == TASK_RUNNING);
 }
 
-#ifndef CONFIG_PREEMPT_RT_FULL
 static inline int ksoftirqd_softirq_pending(void)
 {
 	return local_softirq_pending();
@@ -773,13 +774,10 @@ void irq_enter(void)
 
 static inline void invoke_softirq(void)
 {
-#ifdef CONFIG_PREEMPT_RT_FULL
-	unsigned long flags;
-#endif
-
+#ifndef CONFIG_PREEMPT_RT_FULL
 	if (ksoftirqd_running())
 		return;
-#ifndef CONFIG_PREEMPT_RT_FULL
+
 	if (!force_irqthreads) {
 #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
 		/*
@@ -800,6 +798,7 @@ static inline void invoke_softirq(void)
 		wakeup_softirqd();
 	}
 #else /* PREEMPT_RT_FULL */
+	unsigned long flags;
 
 	local_irq_save(flags);
 	if (__this_cpu_read(ksoftirqd) &&