[PATCH 5/6] workqueue: introduce workqueue_struct->singlethread

[Oleg Nesterov <oleg@tv-sign.ru>]

Add explicit workqueue_struct->singlethread flag. This lessens .text a little,
but most importantly this allows us to manipulate wq->list without changine the
meaning of is_single_threaded().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- 6.20-rc6-mm3/kernel/workqueue.c~5_is_ss	2007-02-07 00:44:52.000000000 +0300
+++ 6.20-rc6-mm3/kernel/workqueue.c	2007-02-07 02:02:06.000000000 +0300
@@ -58,8 +58,9 @@ struct cpu_workqueue_struct {
  */
 struct workqueue_struct {
 	struct cpu_workqueue_struct *cpu_wq;
+	struct list_head list;
 	const char *name;
-	struct list_head list; 	/* Empty if single thread */
+	int singlethread;
 	int freezeable;		/* Freeze threads during suspend */
 };
 
@@ -76,7 +77,7 @@ static cpumask_t cpu_populated_map __rea
 /* If it's single threaded, it isn't in the list of workqueues. */
 static inline int is_single_threaded(struct workqueue_struct *wq)
 {
-	return list_empty(&wq->list);
+	return wq->singlethread;
 }
 
 static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq)
@@ -691,10 +692,11 @@ struct workqueue_struct *__create_workqu
 	}
 
 	wq->name = name;
+	wq->singlethread = singlethread;
 	wq->freezeable = freezeable;
+	INIT_LIST_HEAD(&wq->list);
 
 	if (singlethread) {
-		INIT_LIST_HEAD(&wq->list);
 		cwq = init_cpu_workqueue(wq, singlethread_cpu);
 		err = create_workqueue_thread(cwq, singlethread_cpu);
 	} else {