* Thomas Gleixner | 2014-05-02 21:01:50 [+0200]: >It's different as it CANNOT fail on UP. That's called from the idle >code and there is no way that anything holds that lock on UP when idle >runs.
Okay, so I will add the patch here. The same thing (mostly) but it will also skip the irq_work_needs_cpu() check since we will run the timer softirq anyway. From: Sebastian Andrzej Siewior <[email protected]> Date: Fri, 2 May 2014 21:31:50 +0200 Subject: [PATCH] timer: do not spin_trylock() on UP This will void a warning comming from the spin-lock debugging code. The lock avoiding idea is from Steven Rostedt. Signed-off-by: Sebastian Andrzej Siewior <[email protected]> --- kernel/timer.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/timer.c b/kernel/timer.c index 54596b5..8750875 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1455,18 +1455,31 @@ void run_local_timers(void) struct tvec_base *base = __this_cpu_read(tvec_bases); hrtimer_run_queues(); /* * We can access this lockless as we are in the timer * interrupt. If there are no timers queued, nothing to do in * the timer softirq. */ #ifdef CONFIG_PREEMPT_RT_FULL + +#ifndef CONFIG_SMP + /* + * The spin_do_trylock() later may fail as the lock may be hold before + * the interrupt arrived. The spin-lock debugging code will raise a + * warning if the try_lock fails on UP. Since this is only an + * optimization for the FULL_NO_HZ case (not to run the timer softirq on + * an nohz_full CPU) we don't really care and shedule the softirq. + */ + raise_softirq(TIMER_SOFTIRQ); + return; +#endif + /* On RT, irq work runs from softirq */ if (irq_work_needs_cpu()) { raise_softirq(TIMER_SOFTIRQ); return; } if (!spin_do_trylock(&base->lock)) { raise_softirq(TIMER_SOFTIRQ); return; -- 2.0.0.rc0 >Thanks, > > tglx Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
