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From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:30:20 -0500
Subject: timers: preempt-rt support
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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 */
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