linux-kernel - [PATCH 3/7] workqueue: Add pwq_calculate_max

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Message-Id: <20231227145143.2399-4-jiangshanlai@gmail.com>
Date: Wed, 27 Dec 2023 22:51:39 +0800
From: Lai Jiangshan <jiangshanlai@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>,
	Naohiro.Aota@....com,
	Lai Jiangshan <jiangshan.ljs@...group.com>,
	Lai Jiangshan <jiangshanlai@...il.com>
Subject: [PATCH 3/7] workqueue: Add pwq_calculate_max_active()

From: Lai Jiangshan <jiangshan.ljs@...group.com>

Abstract the code of calculating max_active from pwq_adjust_max_active()
into pwq_calculate_max_active() to make the logic clearer.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
---
 kernel/workqueue.c | 44 +++++++++++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 17 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1f52685498f1..3347ba3a734f 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4136,6 +4136,25 @@ static void pwq_release_workfn(struct kthread_work *work)
 	}
 }
 
+/**
+ * pwq_calculate_max_active - Determine max_active to use
+ * @pwq: pool_workqueue of interest
+ *
+ * Determine the max_active @pwq should use.
+ */
+static int pwq_calculate_max_active(struct pool_workqueue *pwq)
+{
+	/*
+	 * During [un]freezing, the caller is responsible for ensuring
+	 * that pwq_adjust_max_active() is called at least once after
+	 * @workqueue_freezing is updated and visible.
+	 */
+	if ((pwq->wq->flags & WQ_FREEZABLE) && workqueue_freezing)
+		return 0;
+
+	return pwq->wq->saved_max_active;
+}
+
 /**
  * pwq_adjust_max_active - update a pwq's max_active to the current setting
  * @pwq: target pool_workqueue
@@ -4147,35 +4166,26 @@ static void pwq_release_workfn(struct kthread_work *work)
 static void pwq_adjust_max_active(struct pool_workqueue *pwq)
 {
 	struct workqueue_struct *wq = pwq->wq;
-	bool freezable = wq->flags & WQ_FREEZABLE;
+	int max_active = pwq_calculate_max_active(pwq);
 	unsigned long flags;
 
 	/* for @wq->saved_max_active */
 	lockdep_assert_held(&wq->mutex);
 
-	/* fast exit for non-freezable wqs */
-	if (!freezable && pwq->max_active == wq->saved_max_active)
+	/* fast exit if unchanged */
+	if (pwq->max_active == max_active)
 		return;
 
 	/* this function can be called during early boot w/ irq disabled */
 	raw_spin_lock_irqsave(&pwq->pool->lock, flags);
 
-	/*
-	 * During [un]freezing, the caller is responsible for ensuring that
-	 * this function is called at least once after @workqueue_freezing
-	 * is updated and visible.
-	 */
-	if (!freezable || !workqueue_freezing) {
-		pwq->max_active = wq->saved_max_active;
+	pwq->max_active = max_active;
 
-		while (!list_empty(&pwq->inactive_works) &&
-		       pwq->nr_active < pwq->max_active)
-			pwq_activate_first_inactive(pwq);
+	while (!list_empty(&pwq->inactive_works) &&
+	       pwq->nr_active < pwq->max_active)
+		pwq_activate_first_inactive(pwq);
 
-		kick_pool(pwq->pool);
-	} else {
-		pwq->max_active = 0;
-	}
+	kick_pool(pwq->pool);
 
 	raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
 }
-- 
2.19.1.6.gb485710b