1 files changed, 37 insertions, 14 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 52bbf1c842a8..8e2558c2ba67 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -223,7 +223,7 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
 {
         ktime_t now;
 
-        if (rt_bandwidth_enabled() && rt_b->rt_runtime == RUNTIME_INF)
+        if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
                 return;
 
         if (hrtimer_active(&rt_b->rt_period_timer))
@@ -3880,19 +3880,24 @@ int select_nohz_load_balancer(int stop_tick)
         int cpu = smp_processor_id();
 
         if (stop_tick) {
-                cpumask_set_cpu(cpu, nohz.cpu_mask);
                 cpu_rq(cpu)->in_nohz_recently = 1;
 
-                /*
-                 * If we are going offline and still the leader, give up!
-                 */
-                if (!cpu_active(cpu) &&
-                    atomic_read(&nohz.load_balancer) == cpu) {
+                if (!cpu_active(cpu)) {
+                        if (atomic_read(&nohz.load_balancer) != cpu)
+                                return 0;
+
+                        /*
+                         * If we are going offline and still the leader,
+                         * give up!
+                         */
                         if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
                                 BUG();
+
                         return 0;
                 }
 
+                cpumask_set_cpu(cpu, nohz.cpu_mask);
+
                 /* time for ilb owner also to sleep */
                 if (cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
                         if (atomic_read(&nohz.load_balancer) == cpu)
@@ -4687,8 +4692,8 @@ EXPORT_SYMBOL(default_wake_function);
  * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
  * zero in this (rare) case, and we handle it by continuing to scan the queue.
  */
-static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
-                             int nr_exclusive, int sync, void *key)
+void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
+                        int nr_exclusive, int sync, void *key)
 {
         wait_queue_t *curr, *next;
 
@@ -6939,20 +6944,26 @@ static void free_rootdomain(struct root_domain *rd)
 
 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
 {
+        struct root_domain *old_rd = NULL;
         unsigned long flags;
 
         spin_lock_irqsave(&rq->lock, flags);
 
         if (rq->rd) {
-                struct root_domain *old_rd = rq->rd;
+                old_rd = rq->rd;
 
                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
                         set_rq_offline(rq);
 
                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 
-                if (atomic_dec_and_test(&old_rd->refcount))
-                        free_rootdomain(old_rd);
+                /*
+                 * If we dont want to free the old_rt yet then
+                 * set old_rd to NULL to skip the freeing later
+                 * in this function:
+                 */
+                if (!atomic_dec_and_test(&old_rd->refcount))
+                        old_rd = NULL;
         }
 
         atomic_inc(&rd->refcount);
@@ -6963,6 +6974,9 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd)
                 set_rq_online(rq);
 
         spin_unlock_irqrestore(&rq->lock, flags);
+
+        if (old_rd)
+                free_rootdomain(old_rd);
 }
 
 static int __init_refok init_rootdomain(struct root_domain *rd, bool bootmem)
@@ -9210,6 +9224,16 @@ static int sched_rt_global_constraints(void)
 
         return ret;
 }
+
+int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
+{
+        /* Don't accept realtime tasks when there is no way for them to run */
+        if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
+                return 0;
+
+        return 1;
+}
+
 #else /* !CONFIG_RT_GROUP_SCHED */
 static int sched_rt_global_constraints(void)
 {
@@ -9303,8 +9327,7 @@ cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
                       struct task_struct *tsk)
 {
 #ifdef CONFIG_RT_GROUP_SCHED
-        /* Don't accept realtime tasks when there is no way for them to run */
-        if (rt_task(tsk) && cgroup_tg(cgrp)->rt_bandwidth.rt_runtime == 0)
+        if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk))
                 return -EINVAL;
 #else
         /* We don't support RT-tasks being in separate groups */