From 98916bc05c2601e9851f21f61ff0a1bafac806e7 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 24 Jan 2014 15:09:33 -0500 Subject: [PATCH] timer: Raise softirq if there's irq_work [ Talking with Sebastian on IRC, it seems that doing the irq_work_run() from the interrupt in -rt is a bad thing. Here we simply raise the softirq if there's irq work to do. This too boots on my i7 ] After trying hard to figure out why my i7 box was locking up with the new active_timers code, that does not run the timer softirq if there are no active timers, I took an extra look at the softirq handler and noticed that it doesn't just run timer softirqs, it also runs irq work. This was the bug that was locking up the system. It wasn't missing a timer, it was missing irq work. By always doing the irq work callbacks, the system boots fine. The missing irq work callback was the RCU's sp_wakeup() function. No need to check for defined(CONFIG_IRQ_WORK). When that's not set the "irq_work_needs_cpu()" is a static inline that returns false. Signed-off-by: Steven Rostedt Signed-off-by: Sebastian Andrzej Siewior --- kernel/timer.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/timer.c b/kernel/timer.c index c8b16e4bc131..28e78f702353 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1462,8 +1462,13 @@ void run_local_timers(void) return; } #endif - if (!base->active_timers) - goto out; + if (!base->active_timers) { +#ifdef CONFIG_PREEMPT_RT_FULL + /* On RT, irq work runs from softirq */ + if (!irq_work_needs_cpu()) +#endif + goto out; + } /* Check whether the next pending timer has expired */ if (time_before_eq(base->next_timer, jiffies))