linux-kernel - [PATCH 9/9 V3] workqueue: merge the role of rebind_hold to idle

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Date:	Thu, 30 Aug 2012 00:52:00 +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 9/9 V3] workqueue: merge the role of rebind_hold to idle_done

Currently is single pass, we can wait on idle_done instead wait on rebind_hold.
So we can remove rebind_hold and make the code simpler.

Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
 kernel/workqueue.c |   25 +++++++++----------------
 1 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 7e6145b..8253727 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1325,9 +1325,6 @@ struct idle_rebind {
 	int		  idle_cnt;	/* # idle workers to be rebound */
 	struct completion idle_done;	/* all idle workers rebound */
 
-	/* idle workers wait all idles to be rebound */
-	struct completion rebind_hold;
-
 	/*
 	 * notify the rebind_workers() that:
 	 * 1. All idle workers are rebound.
@@ -1352,11 +1349,11 @@ static void idle_worker_rebind(struct worker *worker)
 	WARN_ON(!worker_maybe_bind_and_lock(worker));
 	worker_clr_flags(worker, WORKER_REBIND);
 	if (!--worker->idle_rebind->idle_cnt)
-		complete(&worker->idle_rebind->idle_done);
+		complete_all(&worker->idle_rebind->idle_done);
 	spin_unlock_irq(&worker->pool->gcwq->lock);
 
-	/* we did our part, wait for rebind_workers() to finish up */
-	wait_for_completion(&worker->idle_rebind->rebind_hold);
+	/* It did its part, wait for all other idles to finish up */
+	wait_for_completion(&worker->idle_rebind->idle_done);
 
 	/* noify if all idle worker are done(rebond & wait) */
 	spin_lock_irq(&worker->pool->gcwq->lock);
@@ -1427,14 +1424,12 @@ static void rebind_workers(struct global_cwq *gcwq)
 		lockdep_assert_held(&pool->manager_mutex);
 
 	/*
-	 * Rebind idle workers.  Interlocked both ways in triple waits.
-	 * We wait for workers to rebind via @idle_rebind.idle_done.
-	 * Workers will wait for us via @idle_rebind.rebind_hold.
-	 * And them we wait for workers to leave rebind_hold
-	 * via @idle_rebind.ref_done.
+	 * Rebind idle workers.
+	 * Workers wait each other to rebind via @idle_rebind.idle_done.
+	 * We wait for all idle workers to 1) rebind and 2) finish wait
+	 * and 3) release the ref of @idle_rebind via @idle_rebind.ref_done.
 	 */
 	init_completion(&idle_rebind.idle_done);
-	init_completion(&idle_rebind.rebind_hold);
 	init_completion(&idle_rebind.ref_done);
 	idle_rebind.ref_cnt = 1;
 	idle_rebind.idle_cnt = 1;
@@ -1478,14 +1473,12 @@ static void rebind_workers(struct global_cwq *gcwq)
 	}
 
 	/*
-	 * we will leave rebind_workers(), have to wait until no worker
-	 * has ref to this idle_rebind.
+	 * we will leave rebind_workers(), have to wait until all idles
+	 * are rebound and finish wait.
 	 */
 	if (--idle_rebind.ref_cnt) {
 		--idle_rebind.idle_cnt;
 		spin_unlock_irq(&gcwq->lock);
-		wait_for_completion(&idle_rebind.idle_done);
-		complete_all(&idle_rebind.rebind_hold);
 		wait_for_completion(&idle_rebind.ref_done);
 		spin_lock_irq(&gcwq->lock);
 	}
-- 
1.7.4.4

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