sched: CPU remove deadlock fix

[linux-2.6-omap-h63xx.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index 82cc839c92102c821b941eede9f3d400daff938d..e4bb1dd7b308fce6f47e736b70425f4bc3482c0a 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -399,7 +399,7 @@ struct cfs_rq {
         */
        struct sched_entity *curr, *next, *last;
 
-       unsigned long nr_spread_over;
+       unsigned int nr_spread_over;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
        struct rq *rq;  /* cpu runqueue to which this cfs_rq is attached */
@@ -969,6 +969,14 @@ static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
        }
 }
 
+void task_rq_unlock_wait(struct task_struct *p)
+{
+       struct rq *rq = task_rq(p);
+
+       smp_mb(); /* spin-unlock-wait is not a full memory barrier */
+       spin_unlock_wait(&rq->lock);
+}
+
 static void __task_rq_unlock(struct rq *rq)
        __releases(rq->lock)
 {
@@ -1445,9 +1453,12 @@ static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
 static unsigned long cpu_avg_load_per_task(int cpu)
 {
        struct rq *rq = cpu_rq(cpu);
+       unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
 
-       if (rq->nr_running)
-               rq->avg_load_per_task = rq->load.weight / rq->nr_running;
+       if (nr_running)
+               rq->avg_load_per_task = rq->load.weight / nr_running;
+       else
+               rq->avg_load_per_task = 0;
 
        return rq->avg_load_per_task;
 }
@@ -5860,6 +5871,8 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
        struct rq *rq = cpu_rq(cpu);
        unsigned long flags;
 
+       spin_lock_irqsave(&rq->lock, flags);
+
        __sched_fork(idle);
        idle->se.exec_start = sched_clock();
 
@@ -5867,7 +5880,6 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
        idle->cpus_allowed = cpumask_of_cpu(cpu);
        __set_task_cpu(idle, cpu);
 
-       spin_lock_irqsave(&rq->lock, flags);
        rq->curr = rq->idle = idle;
 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
        idle->oncpu = 1;
@@ -6575,7 +6587,9 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
                        req = list_entry(rq->migration_queue.next,
                                         struct migration_req, list);
                        list_del_init(&req->list);
+                       spin_unlock_irq(&rq->lock);
                        complete(&req->done);
+                       spin_lock_irq(&rq->lock);
                }
                spin_unlock_irq(&rq->lock);
                break;
@@ -6877,15 +6891,17 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
        struct sched_domain *tmp;
 
        /* Remove the sched domains which do not contribute to scheduling. */
-       for (tmp = sd; tmp; tmp = tmp->parent) {
+       for (tmp = sd; tmp; ) {
                struct sched_domain *parent = tmp->parent;
                if (!parent)
                        break;
+
                if (sd_parent_degenerate(tmp, parent)) {
                        tmp->parent = parent->parent;
                        if (parent->parent)
                                parent->parent->child = tmp;
-               }
+               } else
+                       tmp = tmp->parent;
        }
 
        if (sd && sd_degenerate(sd)) {
@@ -7674,6 +7690,7 @@ static int __build_sched_domains(const cpumask_t *cpu_map,
 error:
        free_sched_groups(cpu_map, tmpmask);
        SCHED_CPUMASK_FREE((void *)allmasks);
+       kfree(rd);
        return -ENOMEM;
 #endif
 }
@@ -7775,13 +7792,14 @@ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
  *
  * The passed in 'doms_new' should be kmalloc'd. This routine takes
  * ownership of it and will kfree it when done with it. If the caller
- * failed the kmalloc call, then it can pass in doms_new == NULL,
- * and partition_sched_domains() will fallback to the single partition
- * 'fallback_doms', it also forces the domains to be rebuilt.
+ * failed the kmalloc call, then it can pass in doms_new == NULL &&
+ * ndoms_new == 1, and partition_sched_domains() will fallback to
+ * the single partition 'fallback_doms', it also forces the domains
+ * to be rebuilt.
  *
- * If doms_new==NULL it will be replaced with cpu_online_map.
- * ndoms_new==0 is a special case for destroying existing domains.
- * It will not create the default domain.
+ * If doms_new == NULL it will be replaced with cpu_online_map.
+ * ndoms_new == 0 is a special case for destroying existing domains,
+ * and it will not create the default domain.
  *
  * Call with hotplug lock held
  */