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workqueue: Always queue work items to the newest PWQ for order workqueues

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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: 4c065dbce1 ("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)
This commit is contained in:
Lai Jiangshan 2024-07-03 17:27:41 +08:00 committed by Tejun Heo
parent b2b1f93384
commit 58629d4871
1 changed files with 5 additions and 1 deletions
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6
kernel/workqueue.c
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@ -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 * 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 * running there, in which case the work needs to be queued on that
* pool to guarantee non-reentrancy. * 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); 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; struct worker *worker;
raw_spin_lock(&last_pool->lock); raw_spin_lock(&last_pool->lock);