3 files changed, 60 insertions, 22 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index ea2857b99596..d25acf600a32 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -903,8 +903,8 @@ struct sched_class {
         void (*set_cpus_allowed)(struct task_struct *p,
                                  const cpumask_t *newmask);
 
-        void (*join_domain)(struct rq *rq);
-        void (*leave_domain)(struct rq *rq);
+        void (*rq_online)(struct rq *rq);
+        void (*rq_offline)(struct rq *rq);
 
         void (*switched_from) (struct rq *this_rq, struct task_struct *task,
                                int running);
diff --git a/kernel/sched.c b/kernel/sched.c
index dc0be113f41d..f0ed81b71282 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -529,6 +529,7 @@ struct rq {
         int push_cpu;
         /* cpu of this runqueue: */
         int cpu;
+        int online;
 
         struct task_struct *migration_thread;
         struct list_head migration_queue;
@@ -1498,6 +1499,8 @@ static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
 #endif
 
 #define sched_class_highest (&rt_sched_class)
+#define for_each_class(class) \
+   for (class = sched_class_highest; class; class = class->next)
 
 static inline void inc_load(struct rq *rq, const struct task_struct *p)
 {
@@ -6065,6 +6068,36 @@ static void unregister_sched_domain_sysctl(void)
 }
 #endif
 
+static void set_rq_online(struct rq *rq)
+{
+        if (!rq->online) {
+                const struct sched_class *class;
+
+                cpu_set(rq->cpu, rq->rd->online);
+                rq->online = 1;
+
+                for_each_class(class) {
+                        if (class->rq_online)
+                                class->rq_online(rq);
+                }
+        }
+}
+
+static void set_rq_offline(struct rq *rq)
+{
+        if (rq->online) {
+                const struct sched_class *class;
+
+                for_each_class(class) {
+                        if (class->rq_offline)
+                                class->rq_offline(rq);
+                }
+
+                cpu_clear(rq->cpu, rq->rd->online);
+                rq->online = 0;
+        }
+}
+
 /*
  * migration_call - callback that gets triggered when a CPU is added.
  * Here we can start up the necessary migration thread for the new CPU.
@@ -6102,7 +6135,8 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
                 spin_lock_irqsave(&rq->lock, flags);
                 if (rq->rd) {
                         BUG_ON(!cpu_isset(cpu, rq->rd->span));
-                        cpu_set(cpu, rq->rd->online);
+
+                        set_rq_online(rq);
                 }
                 spin_unlock_irqrestore(&rq->lock, flags);
                 break;
@@ -6163,7 +6197,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
                 spin_lock_irqsave(&rq->lock, flags);
                 if (rq->rd) {
                         BUG_ON(!cpu_isset(cpu, rq->rd->span));
-                        cpu_clear(cpu, rq->rd->online);
+                        set_rq_offline(rq);
                 }
                 spin_unlock_irqrestore(&rq->lock, flags);
                 break;
@@ -6385,20 +6419,16 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
 {
         unsigned long flags;
-        const struct sched_class *class;
 
         spin_lock_irqsave(&rq->lock, flags);
 
         if (rq->rd) {
                 struct root_domain *old_rd = rq->rd;
 
-                for (class = sched_class_highest; class; class = class->next) {
-                        if (class->leave_domain)
-                                class->leave_domain(rq);
-                }
+                if (cpu_isset(rq->cpu, old_rd->online))
+                        set_rq_offline(rq);
 
                 cpu_clear(rq->cpu, old_rd->span);
-                cpu_clear(rq->cpu, old_rd->online);
 
                 if (atomic_dec_and_test(&old_rd->refcount))
                         kfree(old_rd);
@@ -6409,12 +6439,7 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd)
 
         cpu_set(rq->cpu, rd->span);
         if (cpu_isset(rq->cpu, cpu_online_map))
-                cpu_set(rq->cpu, rd->online);
-
-        for (class = sched_class_highest; class; class = class->next) {
-                if (class->join_domain)
-                        class->join_domain(rq);
-        }
+                set_rq_online(rq);
 
         spin_unlock_irqrestore(&rq->lock, flags);
 }
@@ -7824,6 +7849,7 @@ void __init sched_init(void)
                 rq->next_balance = jiffies;
                 rq->push_cpu = 0;
                 rq->cpu = i;
+                rq->online = 0;
                 rq->migration_thread = NULL;
                 INIT_LIST_HEAD(&rq->migration_queue);
                 rq_attach_root(rq, &def_root_domain);
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 44b06d75416e..e4821593d4de 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -12,6 +12,9 @@ static inline int rt_overloaded(struct rq *rq)
 
 static inline void rt_set_overload(struct rq *rq)
 {
+        if (!rq->online)
+                return;
+
         cpu_set(rq->cpu, rq->rd->rto_mask);
         /*
          * Make sure the mask is visible before we set
@@ -26,6 +29,9 @@ static inline void rt_set_overload(struct rq *rq)
 
 static inline void rt_clear_overload(struct rq *rq)
 {
+        if (!rq->online)
+                return;
+
         /* the order here really doesn't matter */
         atomic_dec(&rq->rd->rto_count);
         cpu_clear(rq->cpu, rq->rd->rto_mask);
@@ -394,7 +400,10 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
         if (rt_se_prio(rt_se) < rt_rq->highest_prio) {
                 struct rq *rq = rq_of_rt_rq(rt_rq);
                 rt_rq->highest_prio = rt_se_prio(rt_se);
-                cpupri_set(&rq->rd->cpupri, rq->cpu, rt_se_prio(rt_se));
+
+                if (rq->online)
+                        cpupri_set(&rq->rd->cpupri, rq->cpu,
+                                   rt_se_prio(rt_se));
         }
 #endif
 #ifdef CONFIG_SMP
@@ -448,7 +457,10 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 
         if (rt_rq->highest_prio != highest_prio) {
                 struct rq *rq = rq_of_rt_rq(rt_rq);
-                cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio);
+
+                if (rq->online)
+                        cpupri_set(&rq->rd->cpupri, rq->cpu,
+                                   rt_rq->highest_prio);
         }
 
         update_rt_migration(rq_of_rt_rq(rt_rq));
@@ -1154,7 +1166,7 @@ static void set_cpus_allowed_rt(struct task_struct *p,
 }
 
 /* Assumes rq->lock is held */
-static void join_domain_rt(struct rq *rq)
+static void rq_online_rt(struct rq *rq)
 {
         if (rq->rt.overloaded)
                 rt_set_overload(rq);
@@ -1163,7 +1175,7 @@ static void join_domain_rt(struct rq *rq)
 }
 
 /* Assumes rq->lock is held */
-static void leave_domain_rt(struct rq *rq)
+static void rq_offline_rt(struct rq *rq)
 {
         if (rq->rt.overloaded)
                 rt_clear_overload(rq);
@@ -1331,8 +1343,8 @@ static const struct sched_class rt_sched_class = {
         .load_balance           = load_balance_rt,
         .move_one_task          = move_one_task_rt,
         .set_cpus_allowed       = set_cpus_allowed_rt,
-        .join_domain            = join_domain_rt,
-        .leave_domain           = leave_domain_rt,
+        .rq_online              = rq_online_rt,
+        .rq_offline             = rq_offline_rt,
         .pre_schedule           = pre_schedule_rt,
         .post_schedule          = post_schedule_rt,
         .task_wake_up           = task_wake_up_rt,