From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, tglx@linutronix.de
Cc: linux-kernel@vger.kernel.org, jiangshanlai@gmail.com,
valentin.schneider@arm.com, cai@redhat.com,
vincent.donnefort@arm.com, decui@microsoft.com,
paulmck@kernel.org, vincent.guittot@linaro.org,
rostedt@goodmis.org, tj@kernel.org, peterz@infradead.org
Subject: [PATCH 3/4] workqueue: Tag bound workers with KTHREAD_IS_PER_CPU
Date: Tue, 12 Jan 2021 15:43:47 +0100 [thread overview]
Message-ID: <20210112144843.849135905@infradead.org> (raw)
In-Reply-To: 20210112144344.850850975@infradead.org
Mark the per-cpu workqueue workers as KTHREAD_IS_PER_CPU.
Workqueues have unfortunate semantics in that per-cpu workers are not
default flushed and parked during hotplug, however a subset does
manual flush on hotplug and hard relies on them for correctness.
Therefore play silly games..
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/workqueue.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1861,6 +1861,8 @@ static void worker_attach_to_pool(struct
*/
if (pool->flags & POOL_DISASSOCIATED)
worker->flags |= WORKER_UNBOUND;
+ else
+ kthread_set_per_cpu(worker->task, true);
list_add_tail(&worker->node, &pool->workers);
worker->pool = pool;
@@ -1883,6 +1885,7 @@ static void worker_detach_from_pool(stru
mutex_lock(&wq_pool_attach_mutex);
+ kthread_set_per_cpu(worker->task, false);
list_del(&worker->node);
worker->pool = NULL;
@@ -4919,8 +4922,10 @@ static void unbind_workers(int cpu)
raw_spin_unlock_irq(&pool->lock);
- for_each_pool_worker(worker, pool)
+ for_each_pool_worker(worker, pool) {
+ kthread_set_per_cpu(worker->task, false);
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
+ }
mutex_unlock(&wq_pool_attach_mutex);
@@ -4972,9 +4977,11 @@ static void rebind_workers(struct worker
* of all workers first and then clear UNBOUND. As we're called
* from CPU_ONLINE, the following shouldn't fail.
*/
- for_each_pool_worker(worker, pool)
+ for_each_pool_worker(worker, pool) {
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
pool->attrs->cpumask) < 0);
+ kthread_set_per_cpu(worker->task, true);
+ }
raw_spin_lock_irq(&pool->lock);
next prev parent reply other threads:[~2021-01-12 14:55 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 14:43 [PATCH 0/4] sched: Fix hot-unplug regressions Peter Zijlstra
2021-01-12 14:43 ` [PATCH 2/4] kthread: Extract KTHREAD_IS_PER_CPU Peter Zijlstra
2021-01-12 14:43 ` Peter Zijlstra [this message]
2021-01-12 16:36 ` [PATCH 3/4] workqueue: Tag bound workers with KTHREAD_IS_PER_CPU Lai Jiangshan
2021-01-13 11:43 ` Peter Zijlstra
2021-01-12 17:57 ` Valentin Schneider
2021-01-13 13:28 ` Lai Jiangshan
2021-01-13 14:16 ` Valentin Schneider
2021-01-13 17:52 ` Paul E. McKenney
2021-01-13 18:43 ` Valentin Schneider
2021-01-13 18:59 ` Paul E. McKenney
2021-01-14 13:12 ` Peter Zijlstra
2021-01-14 13:21 ` Valentin Schneider
2021-01-14 15:34 ` Peter Zijlstra
2021-01-16 6:27 ` Lai Jiangshan
2021-01-16 12:45 ` Peter Zijlstra
2021-01-16 14:45 ` Lai Jiangshan
2021-01-16 15:16 ` Peter Zijlstra
2021-01-16 16:14 ` Lai Jiangshan
2021-01-16 18:46 ` Peter Zijlstra
2021-01-17 9:54 ` Peter Zijlstra
2021-01-16 15:13 ` Peter Zijlstra
2021-01-12 14:43 ` [PATCH 4/4] sched: Fix CPU hotplug / tighten is_per_cpu_kthread() Peter Zijlstra
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