From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Valentin Schneider <valentin.schneider@arm.com>,
Peter Zijlstra <peterz@infradead.org>, Qian Cai <cai@redhat.com>,
Vincent Donnefort <vincent.donnefort@arm.com>,
Dexuan Cui <decui@microsoft.com>,
Lai Jiangshan <laijs@linux.alibaba.com>,
Tejun Heo <tj@kernel.org>, Lai Jiangshan <jiangshanlai@gmail.com>
Subject: [PATCH -tip V3 7/8] workqueue: reorganize workqueue_offline_cpu() unbind_workers()
Date: Sat, 26 Dec 2020 10:51:15 +0800 [thread overview]
Message-ID: <20201226025117.2770-8-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20201226025117.2770-1-jiangshanlai@gmail.com>
From: Lai Jiangshan <laijs@linux.alibaba.com>
Just move around the code, no functionality changed.
Only wq_pool_attach_mutex protected region becomes a little larger.
It prepares for later patch protecting wq_online_cpumask
in wq_pool_attach_mutex.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
kernel/workqueue.c | 90 +++++++++++++++++++++++-----------------------
1 file changed, 45 insertions(+), 45 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 94545e6feda5..dd32398edf55 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4896,61 +4896,57 @@ void wq_worker_comm(char *buf, size_t size, struct task_struct *task)
* cpu comes back online.
*/
-static void unbind_workers(int cpu)
+static void unbind_workers(struct worker_pool *pool)
{
- struct worker_pool *pool;
struct worker *worker;
- for_each_cpu_worker_pool(pool, cpu) {
- mutex_lock(&wq_pool_attach_mutex);
- raw_spin_lock_irq(&pool->lock);
+ lockdep_assert_held(&wq_pool_attach_mutex);
- /*
- * We've blocked all attach/detach operations. Make all workers
- * unbound and set DISASSOCIATED. Before this, all workers
- * except for the ones which are still executing works from
- * before the last CPU down must be on the cpu. After
- * this, they may become diasporas.
- */
- for_each_pool_worker(worker, pool)
- worker->flags |= WORKER_UNBOUND;
+ raw_spin_lock_irq(&pool->lock);
- pool->flags |= POOL_DISASSOCIATED;
+ /*
+ * We've blocked all attach/detach operations. Make all workers
+ * unbound and set DISASSOCIATED. Before this, all workers
+ * except for the ones which are still executing works from
+ * before the last CPU down must be on the cpu. After
+ * this, they may become diasporas.
+ */
+ for_each_pool_worker(worker, pool)
+ worker->flags |= WORKER_UNBOUND;
- raw_spin_unlock_irq(&pool->lock);
+ pool->flags |= POOL_DISASSOCIATED;
- for_each_pool_worker(worker, pool)
- WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
+ raw_spin_unlock_irq(&pool->lock);
- mutex_unlock(&wq_pool_attach_mutex);
+ for_each_pool_worker(worker, pool)
+ WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
- /*
- * Call schedule() so that we cross rq->lock and thus can
- * guarantee sched callbacks see the %WORKER_UNBOUND flag.
- * This is necessary as scheduler callbacks may be invoked
- * from other cpus.
- */
- schedule();
+ /*
+ * Call schedule() so that we cross rq->lock and thus can
+ * guarantee sched callbacks see the %WORKER_UNBOUND flag.
+ * This is necessary as scheduler callbacks may be invoked
+ * from other cpus.
+ */
+ schedule();
- /*
- * Sched callbacks are disabled now. Zap nr_running.
- * After this, nr_running stays zero and need_more_worker()
- * and keep_working() are always true as long as the
- * worklist is not empty. This pool now behaves as an
- * unbound (in terms of concurrency management) pool which
- * are served by workers tied to the pool.
- */
- atomic_set(&pool->nr_running, 0);
+ /*
+ * Sched callbacks are disabled now. Zap nr_running.
+ * After this, nr_running stays zero and need_more_worker()
+ * and keep_working() are always true as long as the
+ * worklist is not empty. This pool now behaves as an
+ * unbound (in terms of concurrency management) pool which
+ * are served by workers tied to the pool.
+ */
+ atomic_set(&pool->nr_running, 0);
- /*
- * With concurrency management just turned off, a busy
- * worker blocking could lead to lengthy stalls. Kick off
- * unbound chain execution of currently pending work items.
- */
- raw_spin_lock_irq(&pool->lock);
- wake_up_worker(pool);
- raw_spin_unlock_irq(&pool->lock);
- }
+ /*
+ * With concurrency management just turned off, a busy
+ * worker blocking could lead to lengthy stalls. Kick off
+ * unbound chain execution of currently pending work items.
+ */
+ raw_spin_lock_irq(&pool->lock);
+ wake_up_worker(pool);
+ raw_spin_unlock_irq(&pool->lock);
}
/**
@@ -5122,7 +5118,11 @@ int workqueue_offline_cpu(unsigned int cpu)
if (WARN_ON(cpu != smp_processor_id()))
return -1;
- unbind_workers(cpu);
+ for_each_cpu_worker_pool(pool, cpu) {
+ mutex_lock(&wq_pool_attach_mutex);
+ unbind_workers(pool);
+ mutex_unlock(&wq_pool_attach_mutex);
+ }
mutex_lock(&wq_pool_mutex);
cpumask_clear_cpu(cpu, wq_online_cpumask);
--
2.19.1.6.gb485710b
next prev parent reply other threads:[~2020-12-26 1:52 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-26 2:51 [PATCH -tip V3 0/8] workqueue: break affinity initiatively Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 1/8] workqueue: use cpu_possible_mask instead of cpu_active_mask to break affinity Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 2/8] workqueue: Manually break affinity on pool detachment Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 3/8] workqueue: introduce wq_online_cpumask Lai Jiangshan
2021-01-04 13:56 ` Peter Zijlstra
2021-01-05 2:41 ` Lai Jiangshan
2021-01-05 2:53 ` Lai Jiangshan
2021-01-05 8:23 ` Lai Jiangshan
2021-01-05 13:17 ` Peter Zijlstra
2021-01-05 14:37 ` Lai Jiangshan
2021-01-05 14:40 ` Lai Jiangshan
2021-01-05 16:24 ` Peter Zijlstra
2020-12-26 2:51 ` [PATCH -tip V3 4/8] workqueue: use wq_online_cpumask in restore_unbound_workers_cpumask() Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 5/8] workqueue: Manually break affinity on hotplug for unbound pool Lai Jiangshan
[not found] ` <20201226101631.5448-1-hdanton@sina.com>
2020-12-27 14:04 ` Lai Jiangshan
2020-12-26 2:51 ` [PATCH -tip V3 6/8] workqueue: reorganize workqueue_online_cpu() Lai Jiangshan
2020-12-26 2:51 ` Lai Jiangshan [this message]
2020-12-26 2:51 ` [PATCH -tip V3 8/8] workqueue: Fix affinity of kworkers when attaching into pool Lai Jiangshan
[not found] ` <20201229100639.2086-1-hdanton@sina.com>
2020-12-29 10:13 ` Lai Jiangshan
2021-01-08 11:46 ` [PATCH -tip V3 0/8] workqueue: break affinity initiatively Peter Zijlstra
2021-01-11 10:07 ` Thomas Gleixner
2021-01-11 11:01 ` Peter Zijlstra
2021-01-11 15:00 ` Paul E. McKenney
2021-01-11 17:16 ` Peter Zijlstra
2021-01-11 18:09 ` Paul E. McKenney
2021-01-11 21:50 ` Paul E. McKenney
2021-01-12 17:14 ` Paul E. McKenney
2021-01-12 23:53 ` Paul E. McKenney
2021-01-15 9:11 ` Peter Zijlstra
2021-01-15 13:04 ` Peter Zijlstra
2021-01-16 6:00 ` Lai Jiangshan
2021-01-11 19:21 ` Valentin Schneider
2021-01-11 20:23 ` Peter Zijlstra
2021-01-11 22:47 ` Valentin Schneider
2021-01-12 4:33 ` Lai Jiangshan
2021-01-12 14:53 ` Peter Zijlstra
2021-01-12 15:38 ` Lai Jiangshan
2021-01-13 11:10 ` Peter Zijlstra
2021-01-13 12:00 ` Lai Jiangshan
2021-01-13 12:57 ` Lai Jiangshan
2021-01-12 17:52 ` Valentin Schneider
2021-01-12 14:57 ` Jens Axboe
2021-01-12 15:51 ` Peter Zijlstra
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