workqueue: introduce create_rt_workqueue

create_rt_workqueue will create a real time prioritized workqueue.
This is needed for the conversion of stop_machine to a workqueue based
implementation.
This patch adds yet another parameter to __create_workqueue_key to tell
it that we want an rt workqueue.
However it looks like we rather should have something like "int type"
instead of singlethread, freezable and rt.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 5c158c4..89a5a12 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -149,11 +149,11 @@
 
 extern struct workqueue_struct *
 __create_workqueue_key(const char *name, int singlethread,
-		       int freezeable, struct lock_class_key *key,
+		       int freezeable, int rt, struct lock_class_key *key,
 		       const char *lock_name);
 
 #ifdef CONFIG_LOCKDEP
-#define __create_workqueue(name, singlethread, freezeable)	\
+#define __create_workqueue(name, singlethread, freezeable, rt)	\
 ({								\
 	static struct lock_class_key __key;			\
 	const char *__lock_name;				\
@@ -164,17 +164,19 @@
 		__lock_name = #name;				\
 								\
 	__create_workqueue_key((name), (singlethread),		\
-			       (freezeable), &__key,		\
+			       (freezeable), (rt), &__key,	\
 			       __lock_name);			\
 })
 #else
-#define __create_workqueue(name, singlethread, freezeable)	\
-	__create_workqueue_key((name), (singlethread), (freezeable), NULL, NULL)
+#define __create_workqueue(name, singlethread, freezeable, rt)	\
+	__create_workqueue_key((name), (singlethread), (freezeable), (rt), \
+			       NULL, NULL)
 #endif
 
-#define create_workqueue(name) __create_workqueue((name), 0, 0)
-#define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1)
-#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)
+#define create_workqueue(name) __create_workqueue((name), 0, 0, 0)
+#define create_rt_workqueue(name) __create_workqueue((name), 0, 0, 1)
+#define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1, 0)
+#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0, 0)
 
 extern void destroy_workqueue(struct workqueue_struct *wq);