From: Ingo Molnar Date: Fri, 3 Jul 2009 08:30:20 -0500 Subject: timers: preempt-rt support Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/timer.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) Index: linux-stable/kernel/timer.c =================================================================== --- linux-stable.orig/kernel/timer.c +++ linux-stable/kernel/timer.c @@ -1365,7 +1365,17 @@ 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); @@ -1375,7 +1385,6 @@ unsigned long get_next_timer_interrupt(u if (time_before_eq(expires, now)) return now; - return cmp_next_hrtimer_event(now, expires); } #endif @@ -1765,7 +1774,7 @@ static void __cpuinit migrate_timers(int 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. @@ -1786,7 +1795,7 @@ static void __cpuinit migrate_timers(int 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 */