From 58629d4871e8eb2c385b16a73a8451669db59f39 Mon Sep 17 00:00:00 2001
From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Date: Wed, 3 Jul 2024 17:27:41 +0800
Subject: [PATCH] workqueue: Always queue work items to the newest PWQ for
order workqueues
To ensure non-reentrancy, __queue_work() attempts to enqueue a work
item to the pool of the currently executing worker. This is not only
unnecessary for an ordered workqueue, where order inherently suggests
non-reentrancy, but it could also disrupt the sequence if the item is
not enqueued on the newest PWQ.
Just queue it to the newest PWQ and let order management guarantees
non-reentrancy.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Fixes: 4c065dbce1e8 ("workqueue: Enable unbound cpumask update on ordered workqueues")
Cc: stable@vger.kernel.org # v6.9+
Signed-off-by: Tejun Heo <tj@kernel.org>
(cherry picked from commit 74347be3edfd11277799242766edf844c43dd5d3)
---
kernel/workqueue.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 79a178500a774..e3ab09e70ba9a 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2274,9 +2274,13 @@ static void __queue_work(int cpu, struct workqueue_struct *wq,
* If @work was previously on a different pool, it might still be
* running there, in which case the work needs to be queued on that
* pool to guarantee non-reentrancy.
+ *
+ * For ordered workqueue, work items must be queued on the newest pwq
+ * for accurate order management. Guaranteed order also guarantees
+ * non-reentrancy. See the comments above unplug_oldest_pwq().
*/
last_pool = get_work_pool(work);
- if (last_pool && last_pool != pool) {
+ if (last_pool && last_pool != pool && !(wq->flags & __WQ_ORDERED)) {
struct worker *worker;
raw_spin_lock(&last_pool->lock);
--
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