nohz: prevent tick stop outside of the idle loop

[deliverable/linux.git] / kernel / softirq.c

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 3c44956ee7e2312d30f28bc68a5b9825a7da657a..05f248039d77184527c4912ce8ab527a5689e164 100644 (file)
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -312,7 +312,7 @@ void irq_exit(void)
 #ifdef CONFIG_NO_HZ
        /* Make sure that timer wheel updates are propagated */
        if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched())
-               tick_nohz_stop_sched_tick();
+               tick_nohz_stop_sched_tick(0);
        rcu_irq_exit();
 #endif
        preempt_enable_no_resched();
@@ -589,16 +589,20 @@ static void takeover_tasklets(unsigned int cpu)
        local_irq_disable();
 
        /* Find end, append list for that CPU. */
-       *__get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).head;
-       __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail;
-       per_cpu(tasklet_vec, cpu).head = NULL;
-       per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
+       if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) {
+               *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head;
+               __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail;
+               per_cpu(tasklet_vec, cpu).head = NULL;
+               per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
+       }
        raise_softirq_irqoff(TASKLET_SOFTIRQ);
 
-       *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head;
-       __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail;
-       per_cpu(tasklet_hi_vec, cpu).head = NULL;
-       per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
+       if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) {
+               *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head;
+               __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail;
+               per_cpu(tasklet_hi_vec, cpu).head = NULL;
+               per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
+       }
        raise_softirq_irqoff(HI_SOFTIRQ);
 
        local_irq_enable();