linux-kernel - [PATCH 2/6] workqueue: new day don't need WORKER

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Date:	Sat, 15 Sep 2012 16:13:35 +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 2/6] workqueue: new day don't need WORKER_REBIND for busy rebinding

because old busy_worker_rebind_fn() have to wait until all idle worker finish.
so we have to use two flags WORKER_UNBOUND and WORKER_REBIND to avoid
prematurely clear all NOT_RUNNING bit when highly frequent offline/online.

but current code don't need to wait idle workers nor release gcwq->lock
when it is doing rebind in rebind_workers(), so we don't need to use two flags,
just one is enough. remove WORKER_REBIND from busy rebinding.

Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
 kernel/workqueue.c |    8 +-------
 1 files changed, 1 insertions(+), 7 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e8b28d6..4b1ff46 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1641,7 +1641,7 @@ static void busy_worker_rebind_fn(struct work_struct *work)
 	struct global_cwq *gcwq = worker->pool->gcwq;
 
 	if (worker_maybe_bind_and_lock(worker))
-		worker_clr_flags(worker, WORKER_REBIND);
+		worker_clr_flags(worker, WORKER_UNBOUND);
 
 	spin_unlock_irq(&gcwq->lock);
 }
@@ -1696,15 +1696,9 @@ static void rebind_workers(struct global_cwq *gcwq)
 
 	/* rebind busy workers */
 	for_each_busy_worker(worker, i, pos, gcwq) {
-		unsigned long worker_flags = worker->flags;
 		struct work_struct *rebind_work = &worker->rebind_work;
 		struct workqueue_struct *wq;
 
-		/* morph UNBOUND to REBIND atomically */
-		worker_flags &= ~WORKER_UNBOUND;
-		worker_flags |= WORKER_REBIND;
-		ACCESS_ONCE(worker->flags) = worker_flags;
-
 		if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
 				     work_data_bits(rebind_work)))
 			continue;
-- 
1.7.4.4

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