workqueue: factor out start_flush_work()
Factor out start_flush_work() from flush_work(). start_flush_work() has @wait_executing argument which controls whether the barrier is queued only if the work is pending or also if executing. As flush_work() needs to wait for execution too, it uses %true. This commit doesn't cause any behavior difference. start_flush_work() will be used to implement flush_work_sync(). Signed-off-by: Tejun Heo <tj@kernel.org>
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401a8d048e
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baf59022c3
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@ -2326,6 +2326,48 @@ out_unlock:
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}
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EXPORT_SYMBOL_GPL(flush_workqueue);
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static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
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bool wait_executing)
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{
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struct worker *worker = NULL;
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struct global_cwq *gcwq;
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struct cpu_workqueue_struct *cwq;
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might_sleep();
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gcwq = get_work_gcwq(work);
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if (!gcwq)
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return false;
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spin_lock_irq(&gcwq->lock);
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if (!list_empty(&work->entry)) {
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/*
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* See the comment near try_to_grab_pending()->smp_rmb().
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* If it was re-queued to a different gcwq under us, we
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* are not going to wait.
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*/
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smp_rmb();
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cwq = get_work_cwq(work);
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if (unlikely(!cwq || gcwq != cwq->gcwq))
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goto already_gone;
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} else if (wait_executing) {
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worker = find_worker_executing_work(gcwq, work);
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if (!worker)
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goto already_gone;
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cwq = worker->current_cwq;
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} else
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goto already_gone;
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insert_wq_barrier(cwq, barr, work, worker);
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spin_unlock_irq(&gcwq->lock);
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lock_map_acquire(&cwq->wq->lockdep_map);
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lock_map_release(&cwq->wq->lockdep_map);
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return true;
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already_gone:
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spin_unlock_irq(&gcwq->lock);
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return false;
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}
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/**
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* flush_work - wait for a work to finish executing the last queueing instance
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* @work: the work to flush
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@ -2346,46 +2388,14 @@ EXPORT_SYMBOL_GPL(flush_workqueue);
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*/
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bool flush_work(struct work_struct *work)
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{
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struct worker *worker = NULL;
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struct global_cwq *gcwq;
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struct cpu_workqueue_struct *cwq;
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struct wq_barrier barr;
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might_sleep();
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gcwq = get_work_gcwq(work);
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if (!gcwq)
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return 0;
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spin_lock_irq(&gcwq->lock);
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if (!list_empty(&work->entry)) {
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/*
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* See the comment near try_to_grab_pending()->smp_rmb().
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* If it was re-queued to a different gcwq under us, we
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* are not going to wait.
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*/
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smp_rmb();
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cwq = get_work_cwq(work);
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if (unlikely(!cwq || gcwq != cwq->gcwq))
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goto already_gone;
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} else {
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worker = find_worker_executing_work(gcwq, work);
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if (!worker)
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goto already_gone;
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cwq = worker->current_cwq;
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}
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insert_wq_barrier(cwq, &barr, work, worker);
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spin_unlock_irq(&gcwq->lock);
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lock_map_acquire(&cwq->wq->lockdep_map);
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lock_map_release(&cwq->wq->lockdep_map);
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wait_for_completion(&barr.done);
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destroy_work_on_stack(&barr.work);
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return true;
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already_gone:
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spin_unlock_irq(&gcwq->lock);
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return false;
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if (start_flush_work(work, &barr, true)) {
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wait_for_completion(&barr.done);
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destroy_work_on_stack(&barr.work);
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return true;
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} else
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return false;
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}
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EXPORT_SYMBOL_GPL(flush_work);
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