sched: move_task_off_dead_cpu(): Take rq->lock around select_fallback_rq()

[safe/jmp/linux-2.6] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index c0b3ebc..27774b5 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5448,29 +5448,29 @@ static int migration_thread(void *data)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-
-static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
-{
-       int ret;
-
-       local_irq_disable();
-       ret = __migrate_task(p, src_cpu, dest_cpu);
-       local_irq_enable();
-       return ret;
-}
-
 /*
  * Figure out where task on dead CPU should go, use force if necessary.
  */
 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
 {
-       int dest_cpu;
-
+       struct rq *rq = cpu_rq(dead_cpu);
+       int needs_cpu, uninitialized_var(dest_cpu);
+       unsigned long flags;
 again:
-       dest_cpu = select_fallback_rq(dead_cpu, p);
+       local_irq_save(flags);
+
+       raw_spin_lock(&rq->lock);
+       needs_cpu = (task_cpu(p) == dead_cpu) && (p->state != TASK_WAKING);
+       if (needs_cpu)
+               dest_cpu = select_fallback_rq(dead_cpu, p);
+       raw_spin_unlock(&rq->lock);
 
        /* It can have affinity changed while we were choosing. */
-       if (unlikely(!__migrate_task_irq(p, dead_cpu, dest_cpu)))
+       if (needs_cpu)
+               needs_cpu = !__migrate_task(p, dead_cpu, dest_cpu);
+       local_irq_restore(flags);
+
+       if (unlikely(needs_cpu))
                goto again;
 }