hrtimer: simplify hotplug migration

Impact: cleanup

No need for a smp function call, which is likely to run on the same
CPU anyway. We can just call hrtimers_peek_ahead() in the interrupts
disabled section of migrate_hrtimers().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 10 insertions, 15 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 9c2bfa841281..8010a67cead0 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1504,11 +1504,6 @@ static void __cpuinit init_hrtimers_cpu(int cpu)
 
 #ifdef CONFIG_HOTPLUG_CPU
 
-static void tickle_timers(void *arg)
-{
-        hrtimer_peek_ahead_timers();
-}
-
 static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
                                 struct hrtimer_clock_base *new_base)
 {
@@ -1547,20 +1542,19 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
 static void migrate_hrtimers(int scpu)
 {
         struct hrtimer_cpu_base *old_base, *new_base;
-        int dcpu, i;
+        int i;
 
         BUG_ON(cpu_online(scpu));
-        old_base = &per_cpu(hrtimer_bases, scpu);
-        new_base = &get_cpu_var(hrtimer_bases);
-
-        dcpu = smp_processor_id();
-
         tick_cancel_sched_timer(scpu);
+
+        local_irq_disable();
+        old_base = &per_cpu(hrtimer_bases, scpu);
+        new_base = &__get_cpu_var(hrtimer_bases);
         /*
          * The caller is globally serialized and nobody else
          * takes two locks at once, deadlock is not possible.
          */
-        spin_lock_irq(&new_base->lock);
+        spin_lock(&new_base->lock);
         spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
 
         for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
@@ -1569,10 +1563,11 @@ static void migrate_hrtimers(int scpu)
         }
 
         spin_unlock(&old_base->lock);
-        spin_unlock_irq(&new_base->lock);
-        put_cpu_var(hrtimer_bases);
+        spin_unlock(&new_base->lock);
 
-        smp_call_function_single(dcpu, tickle_timers, NULL, 0);
+        /* Check, if we got expired work to do */
+        __hrtimer_peek_ahead_timers();
+        local_irq_enable();
 }
 
 #endif /* CONFIG_HOTPLUG_CPU */