linux-kernel - [PATCH 20/21] workqueue: modify wq->freezing only when freezable

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Date:	Wed, 20 Mar 2013 03:28:20 +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 20/21] workqueue: modify wq->freezing only when freezable

simplify pwq_adjust_max_active().
make freeze_workqueues_begin() and thaw_workqueues() fast skip non-freezable wq.

Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
 kernel/workqueue.c |   18 ++++++++++--------
 1 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 882fe87..ce8fd7b 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3487,18 +3487,15 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
 static void pwq_adjust_max_active(struct pool_workqueue *pwq)
 {
 	struct workqueue_struct *wq = pwq->wq;
-	bool freezable = wq->flags & WQ_FREEZABLE;
 
 	/* for @wq->saved_max_active and @wq->freezing */
 	lockdep_assert_held(&wq->mutex);
+	if (WARN_ON_ONCE(!(wq->flags & WQ_FREEZABLE) && wq->freezing))
+		wq->freezing = false;
 
-	/* fast exit for non-freezable wqs */
-	if (!freezable && pwq->max_active == wq->saved_max_active)
-		return;
-
-	if (freezable && wq->freezing) {
+	if (wq->freezing) {
 		pwq->max_active = 0;
-	} else {
+	} else if (pwq->max_active != wq->saved_max_active) {
 		spin_lock_irq(&pwq->pool->lock);
 		pwq->max_active = wq->saved_max_active;
 
@@ -3711,7 +3708,8 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
 	mutex_lock(&wqs_mutex);
 
 	mutex_lock(&wq->mutex);
-	wq->freezing = workqueue_freezing;
+	if (wq->flags & WQ_FREEZABLE)
+		wq->freezing = workqueue_freezing;
 	for_each_pwq(pwq, wq)
 		pwq_adjust_max_active(pwq);
 	mutex_unlock(&wq->mutex);
@@ -4206,6 +4204,8 @@ void freeze_workqueues_begin(void)
 	workqueue_freezing = true;
 
 	list_for_each_entry(wq, &workqueues, list) {
+		if (!(wq->flags & WQ_FREEZABLE))
+			continue;
 		mutex_lock(&wq->mutex);
 		/* set FREEZING */
 		WARN_ON_ONCE(wq->freezing);
@@ -4286,6 +4286,8 @@ void thaw_workqueues(void)
 	workqueue_freezing = false;
 
 	list_for_each_entry(wq, &workqueues, list) {
+		if (!(wq->flags & WQ_FREEZABLE))
+			continue;
 		mutex_lock(&wq->mutex);
 		/* clear FREEZING */
 		WARN_ON_ONCE(!wq->freezing);
-- 
1.7.7.6

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