linux-kernel - [PATCH 4/7] workqueue: single pass rebind

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Date:	Tue, 28 Aug 2012 01:58:24 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Cc:	Lai Jiangshan <laijs@...fujitsu.com>
Subject: [PATCH 4/7] workqueue: single pass rebind_workers

busy_worker_rebind_fn() can't return until all idle workers are rebound,
the code of busy_worker_rebind_fn() ensure this.

So we can change the order of the code of rebind_workers(),
and make it a single pass do the rebind_workers().

It makes the code much clean and better readability.

Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
 kernel/workqueue.c |   19 +++++++------------
 1 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f6e4394..96485c0 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1394,16 +1394,12 @@ static void rebind_workers(struct global_cwq *gcwq)
 	 * us to finish up by competing on pool->manager_mutex.
 	 */
 	init_completion(&idle_rebind.done);
-retry:
 	idle_rebind.cnt = 1;
 	INIT_COMPLETION(idle_rebind.done);
 
 	/* set REBIND and kick idle ones, we'll wait for these later */
 	for_each_worker_pool(pool, gcwq) {
 		list_for_each_entry(worker, &pool->idle_list, entry) {
-			if (!(worker->flags & WORKER_UNBOUND))
-				continue;
-
 			/* morph UNBOUND to REBIND */
 			worker->flags &= ~WORKER_UNBOUND;
 			worker->flags |= WORKER_REBIND;
@@ -1416,14 +1412,6 @@ retry:
 		}
 	}
 
-	if (--idle_rebind.cnt) {
-		spin_unlock_irq(&gcwq->lock);
-		wait_for_completion(&idle_rebind.done);
-		spin_lock_irq(&gcwq->lock);
-		/* busy ones might have become idle while waiting, retry */
-		goto retry;
-	}
-
 	/* rebind busy workers */
 	for_each_busy_worker(worker, i, pos, gcwq) {
 		struct work_struct *rebind_work = &worker->rebind_work;
@@ -1442,6 +1430,13 @@ retry:
 			    worker->scheduled.next,
 			    work_color_to_flags(WORK_NO_COLOR));
 	}
+
+	/* waiting for all idle workers to be rebound */
+	if (--idle_rebind.cnt) {
+		spin_unlock_irq(&gcwq->lock);
+		wait_for_completion(&idle_rebind.done);
+		spin_lock_irq(&gcwq->lock);
+	}
 }
 
 static struct worker *alloc_worker(void)
-- 
1.7.4.4

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