[patch-rt] softirq: Move ksoftirqd_running() under !CONFIG_PREEMPT_RT_FULL

From: Mike Galbraith
Date: Sat Dec 31 2016 - 03:20:34 EST



Otherwise, ktimersoftd may not be awakened when it has work to do.

[ 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

Signed-off-by: Mike Galbraith <efault@xxxxxx>
---
kernel/softirq.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -206,6 +206,7 @@ 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 +218,6 @@ 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();
@@ -794,13 +794,10 @@ 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
/*
@@ -821,6 +818,7 @@ static inline void invoke_softirq(void)
wakeup_softirqd();
}
#else /* PREEMPT_RT_FULL */
+ unsigned long flags;

local_irq_save(flags);
if (__this_cpu_read(ksoftirqd) &&