From: Mike Galbraith 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 Signed-off-by: Sebastian Andrzej Siewior --- kernel/softirq.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -28,6 +28,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -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) &&