workqueue: implement WQ_NON_REENTRANT

With gcwq managing all the workers and work->data pointing to the last
gcwq it was on, non-reentrance can be easily implemented by checking
whether the work is still running on the previous gcwq on queueing.
Implement it.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 0a7814131e66..07cf5e5f91cb 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -225,6 +225,7 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
 enum {
         WQ_FREEZEABLE           = 1 << 0, /* freeze during suspend */
         WQ_SINGLE_CPU           = 1 << 1, /* only single cpu at a time */
+        WQ_NON_REENTRANT        = 1 << 2, /* guarantee non-reentrance */
 };
 
 extern struct workqueue_struct *