Merge branch '20120221_isdn' of git://repo.or.cz/linux-2.6/trivial-mods

[cascardo/linux.git] / kernel / sched / fair.c

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 84adb2d..7c6414f 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4866,6 +4866,15 @@ static void nohz_balancer_kick(int cpu)
        return;
 }
 
+static inline void clear_nohz_tick_stopped(int cpu)
+{
+       if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
+               cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
+               atomic_dec(&nohz.nr_cpus);
+               clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
+       }
+}
+
 static inline void set_cpu_sd_state_busy(void)
 {
        struct sched_domain *sd;
@@ -4904,6 +4913,12 @@ void select_nohz_load_balancer(int stop_tick)
 {
        int cpu = smp_processor_id();
 
+       /*
+        * If this cpu is going down, then nothing needs to be done.
+        */
+       if (!cpu_active(cpu))
+               return;
+
        if (stop_tick) {
                if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
                        return;
@@ -4914,6 +4929,18 @@ void select_nohz_load_balancer(int stop_tick)
        }
        return;
 }
+
+static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
+                                       unsigned long action, void *hcpu)
+{
+       switch (action & ~CPU_TASKS_FROZEN) {
+       case CPU_DYING:
+               clear_nohz_tick_stopped(smp_processor_id());
+               return NOTIFY_OK;
+       default:
+               return NOTIFY_DONE;
+       }
+}
 #endif
 
 static DEFINE_SPINLOCK(balancing);
@@ -5070,11 +5097,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu)
        * busy tick after returning from idle, we will update the busy stats.
        */
        set_cpu_sd_state_busy();
-       if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
-               clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
-               cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
-               atomic_dec(&nohz.nr_cpus);
-       }
+       clear_nohz_tick_stopped(cpu);
 
        /*
         * None are in tickless mode and hence no need for NOHZ idle load
@@ -5590,6 +5613,7 @@ __init void init_sched_fair_class(void)
 
 #ifdef CONFIG_NO_HZ
        zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
+       cpu_notifier(sched_ilb_notifier, 0);
 #endif
 #endif /* SMP */