linux-kernel - [PATCH 2/4] workqueue: Don't bind the rescuer in the last working cpu

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Message-Id: <20240621073225.3600-3-jiangshanlai@gmail.com>
Date: Fri, 21 Jun 2024 15:32:23 +0800
From: Lai Jiangshan <jiangshanlai@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@...group.com>,
	Valentin Schneider <vschneid@...hat.com>,
	Tejun Heo <tj@...nel.org>,
	Lai Jiangshan <jiangshanlai@...il.com>
Subject: [PATCH 2/4] workqueue: Don't bind the rescuer in the last working cpu

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

So that when the rescuer is woken up next time, it will not interrupt
the last working cpu which might be busy on other crucial works but
have nothing to do with the rescuer's incoming works.

Cc: Valentin Schneider <vschneid@...hat.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
---
 kernel/workqueue.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index a0fb2f60e938..93b87ca63a7e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2684,6 +2684,17 @@ static void worker_attach_to_pool(struct worker *worker,
 	mutex_unlock(&wq_pool_attach_mutex);
 }
 
+static void unbind_worker(struct worker *worker)
+{
+	lockdep_assert_held(&wq_pool_attach_mutex);
+
+	kthread_set_per_cpu(worker->task, -1);
+	if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask))
+		WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0);
+	else
+		WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
+}
+
 /**
  * worker_detach_from_pool() - detach a worker from its pool
  * @worker: worker which is attached to its pool
@@ -2701,7 +2712,7 @@ static void worker_detach_from_pool(struct worker *worker)
 
 	mutex_lock(&wq_pool_attach_mutex);
 
-	kthread_set_per_cpu(worker->task, -1);
+	unbind_worker(worker);
 	list_del(&worker->node);
 	worker->pool = NULL;
 
@@ -2796,17 +2807,6 @@ static struct worker *create_worker(struct worker_pool *pool)
 	return NULL;
 }
 
-static void unbind_worker(struct worker *worker)
-{
-	lockdep_assert_held(&wq_pool_attach_mutex);
-
-	kthread_set_per_cpu(worker->task, -1);
-	if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask))
-		WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0);
-	else
-		WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
-}
-
 static void wake_dying_workers(struct list_head *cull_list)
 {
 	struct worker *worker;
-- 
2.19.1.6.gb485710b