workqueue: add WARN_ON_ONCE() on CPU number to wq_worker_waking_up()

Recently, workqueue code has gone through some changes and we found
some bugs related to concurrency management operations happening on
the wrong CPU.  When a worker is concurrency managed
(!WORKER_NOT_RUNNIG), it should be bound to its associated cpu and
woken up to that cpu.  Add WARN_ON_ONCE() to verify this.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 26f5d16aef65264d138fb83d28cf6b15d881d70d..ae9a05603e01ba5eb6cd004e70e796802c8cd1eb 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -739,8 +739,10 @@ void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
 {
        struct worker *worker = kthread_data(task);
 
-       if (!(worker->flags & WORKER_NOT_RUNNING))
+       if (!(worker->flags & WORKER_NOT_RUNNING)) {
+               WARN_ON_ONCE(worker->pool->gcwq->cpu != cpu);
                atomic_inc(get_pool_nr_running(worker->pool));
+       }
 }
 
 /**