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-rw-r--r--kernel/workqueue.c46
1 files changed, 46 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index d9a2d65cc63e..ee41cf857d55 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -423,6 +423,52 @@ void flush_workqueue(struct workqueue_struct *wq)
}
EXPORT_SYMBOL_GPL(flush_workqueue);
+/**
+ * flush_work - block until a work_struct's callback has terminated
+ * @work: the work which is to be flushed
+ *
+ * It is expected that, prior to calling flush_work(), the caller has
+ * arranged for the work to not be requeued, otherwise it doesn't make
+ * sense to use this function.
+ */
+int flush_work(struct work_struct *work)
+{
+ struct cpu_workqueue_struct *cwq;
+ struct list_head *prev;
+ struct wq_barrier barr;
+
+ might_sleep();
+ cwq = get_wq_data(work);
+ if (!cwq)
+ return 0;
+
+ prev = NULL;
+ spin_lock_irq(&cwq->lock);
+ if (!list_empty(&work->entry)) {
+ /*
+ * See the comment near try_to_grab_pending()->smp_rmb().
+ * If it was re-queued under us we are not going to wait.
+ */
+ smp_rmb();
+ if (unlikely(cwq != get_wq_data(work)))
+ goto out;
+ prev = &work->entry;
+ } else {
+ if (cwq->current_work != work)
+ goto out;
+ prev = &cwq->worklist;
+ }
+ insert_wq_barrier(cwq, &barr, prev->next);
+out:
+ spin_unlock_irq(&cwq->lock);
+ if (!prev)
+ return 0;
+
+ wait_for_completion(&barr.done);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(flush_work);
+
/*
* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
* so this work can't be re-armed in any way.