linux-kernel - [PATCH 10/10 V4] workqueue: merge the role of rebind_hold to idle

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Date:	Sun, 2 Sep 2012 00:28:28 +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 10/10 V4] 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 |   35 +++++++++++------------------------
 1 files changed, 11 insertions(+), 24 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 6d68571..6411616 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1309,9 +1309,6 @@ 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.
@@ -1340,7 +1337,7 @@ static void synchronize_all_idles_rebound(struct global_cwq *gcwq,
 {
 
 	/* wait for rebind_workers() to notify that all idles are rebound */
-	wait_for_completion(&idle_rebind->rebind_hold);
+	wait_for_completion(&idle_rebind->idle_done);
 
 	/* finished synchronizing, put reference */
 	spin_lock_irq(&gcwq->lock);
@@ -1371,7 +1368,7 @@ static void idle_worker_rebind(struct worker *worker)
 
 	/* this worker has been rebound */
 	if (!--idle_rebind->idle_cnt)
-		complete(&idle_rebind->idle_done);
+		complete_all(&idle_rebind->idle_done);
 	spin_unlock_irq(&gcwq->lock);
 
 	synchronize_all_idles_rebound(gcwq, idle_rebind);
@@ -1447,17 +1444,15 @@ 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. Idle workers wait each other to rebind via
+	 * synchronize_all_idles_rebound(). We wait for all idle workers
+	 * to rebind via synchronize_all_idles_rebound() too.
+	 * And them we wait for all workers finish synchronizing and
+	 * 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;
-	gcwq->idle_rebind = &idle_rebind;
 	idle_rebind.idle_cnt = 1;
 
 	/* set REBIND and kick idle ones, we'll wait for these later */
@@ -1497,23 +1492,15 @@ 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 until no worker has ref to this idle_rebind.
 	 */
 	if (--idle_rebind.idle_cnt) {
+		gcwq->idle_rebind = &idle_rebind;
 		spin_unlock_irq(&gcwq->lock);
-		wait_for_completion(&idle_rebind.idle_done);
-		spin_lock_irq(&gcwq->lock);
-	}
-
-	complete_all(&idle_rebind.rebind_hold);
-
-	if (--idle_rebind.ref_cnt) {
-		spin_unlock_irq(&gcwq->lock);
+		synchronize_all_idles_rebound(gcwq, &idle_rebind);
 		wait_for_completion(&idle_rebind.ref_done);
 		spin_lock_irq(&gcwq->lock);
-	} else {
-		gcwq->idle_rebind = NULL;
 	}
 }
 
-- 
1.7.4.4

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