Merge branch 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/adobriyan...

[linux-2.6-block.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index 52bbf1c842a8e0baecd1cd9f53883806eaab1350..410eec404133fd267eb80041395e21d266f0e552 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -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)