From: Ingo Molnar Date: Fri, 3 Jul 2009 08:30:20 -0500 Subject: timers: preempt-rt support Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/3.14/patches-3.14.0-rt1.tar.xz Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/timer.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1358,7 +1358,17 @@ unsigned long get_next_timer_interrupt(u if (cpu_is_offline(smp_processor_id())) return expires; +#ifdef CONFIG_PREEMPT_RT_FULL + /* + * On PREEMPT_RT we cannot sleep here. If the trylock does not + * succeed then we return the worst-case 'expires in 1 tick' + * value: + */ + if (!spin_trylock(&base->lock)) + return now + 1; +#else spin_lock(&base->lock); +#endif if (base->active_timers) { if (time_before_eq(base->next_timer, base->timer_jiffies)) base->next_timer = __next_timer_interrupt(base); @@ -1368,7 +1378,6 @@ unsigned long get_next_timer_interrupt(u if (time_before_eq(expires, now)) return now; - return cmp_next_hrtimer_event(now, expires); } #endif @@ -1618,7 +1627,7 @@ static void migrate_timers(int cpu) BUG_ON(cpu_online(cpu)); old_base = per_cpu(tvec_bases, cpu); - new_base = get_cpu_var(tvec_bases); + new_base = get_local_var(tvec_bases); /* * The caller is globally serialized and nobody else * takes two locks at once, deadlock is not possible. @@ -1639,7 +1648,7 @@ static void migrate_timers(int cpu) spin_unlock(&old_base->lock); spin_unlock_irq(&new_base->lock); - put_cpu_var(tvec_bases); + put_local_var(tvec_bases); } #endif /* CONFIG_HOTPLUG_CPU */