[PATCH] Revert "workqueue: remove unused cancel_work()"

[Andrey Grodzovsky <andrey.grodzovsky@amd.com>]

This reverts commit 6417250d3f894e66a68ba1cd93676143f2376a6f
and exports the function. 

We need this funtion in amdgpu driver to fix a bug.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
---
 include/linux/workqueue.h | 1 +
 kernel/workqueue.c        | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 7fee9b6cfede..9e41e1226193 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -453,6 +453,7 @@ extern int schedule_on_each_cpu(work_func_t func);
 int execute_in_process_context(work_func_t fn, struct execute_work *);
 
 extern bool flush_work(struct work_struct *work);
+extern bool cancel_work(struct work_struct *work);
 extern bool cancel_work_sync(struct work_struct *work);
 
 extern bool flush_delayed_work(struct delayed_work *dwork);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 613917bbc4e7..f94b596ebffd 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3267,6 +3267,15 @@ static bool __cancel_work(struct work_struct *work, bool is_dwork)
 	return ret;
 }
 
+/*
+ * See cancel_delayed_work()
+ */
+bool cancel_work(struct work_struct *work)
+{
+	return __cancel_work(work, false);
+}
+EXPORT_SYMBOL(cancel_work);
+
 /**
  * cancel_delayed_work - cancel a delayed work
  * @dwork: delayed_work to cancel
-- 
2.25.1