/**
 * queue_work - queue work on a workqueue
 * @wq: workqueue to use
 * @work: work to queue
 *
 * Returns 0 if @work was already on a queue, non-zero otherwise.
 *
 * We queue the work to the CPU on which it was submitted, but if the CPU dies
 * it can be processed by another CPU.
 */
int queue_work(struct workqueue_struct *wq, struct work_struct *work)
{
 int ret;

 ret = queue_work_on(get_cpu(), wq, work);
 put_cpu();

 return ret;
}

/**
 * queue_work_on - queue work on specific cpu
 * @cpu: CPU number to execute work on
 * @wq: workqueue to use
 * @work: work to queue
 *
 * Returns 0 if @work was already on a queue, non-zero otherwise.
 *
 * We queue the work to a specific CPU, the caller must ensure it
 * can't go away.
 */
int
queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
{
 int ret = 0;

 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
  BUG_ON(!list_empty(&work->entry));
  __queue_work(wq_per_cpu(wq, cpu), work);
  ret = 1;
 }
 return ret;
}

static void insert_work(struct cpu_workqueue_struct *cwq,
   struct work_struct *work, struct list_head *head)
{
 trace_workqueue_insertion(cwq->thread, work);

 set_wq_data(work, cwq);
 /*
  * Ensure that we get the right work->data if we see the
  * result of list_add() below, see try_to_grab_pending().
  */
 smp_wmb();
 list_add_tail(&work->entry, head);
 wake_up(&cwq->more_work);
}