| Message ID | 20191211112229.22652-1-hdanton@sina.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | workqueue: fix selecting cpu for queuing work and cleanup | expand |
On Wed, Dec 11, 2019 at 07:22:29PM +0800, Hillf Danton wrote:
> Release rcu lock to reap dead pool workqueue.
What's to be gained by reaping the pwq (and possibly worker pool and wq) before
__queue_work() retries? It'll just happen after the queueing finishes.
On Wed, 11 Dec 2019 18:25:04 -0500 Daniel Jordan wrote: > On Wed, Dec 11, 2019 at 07:22:29PM +0800, Hillf Danton wrote: > > Release rcu lock to reap dead pool workqueue. > > What's to be gained by reaping the pwq (and possibly worker pool and wq) before > __queue_work() retries? It'll just happen after the queueing finishes. Releasing rcu lock just says that the dead pwp no longer makes sense on the local cpu and it can go now, without the local queuing work AFAICS affected because of irq disabled. But it's hard to say how it will be reclaimed on other cpus, say before this queuing ends, and this does not matter in terms of the local queuing. Hillf
--- d/kernel/workqueue.c +++ e/kernel/workqueue.c @@ -1409,9 +1409,9 @@ static void __queue_work(int cpu, struct if (unlikely(wq->flags & __WQ_DRAINING) && WARN_ON_ONCE(!is_chained_work(wq))) return; - - rcu_read_lock(); retry: + rcu_read_lock(); + /* pwq which will be used unless @work is executing elsewhere */ if (wq->flags & WQ_UNBOUND) { if (req_cpu == WORK_CPU_UNBOUND) @@ -1458,6 +1458,7 @@ retry: if (unlikely(!pwq->refcnt)) { if (wq->flags & WQ_UNBOUND) { spin_unlock(&pwq->pool->lock); + rcu_read_unlock(); cpu_relax(); goto retry; }
Release rcu lock to reap dead pool workqueue. Signed-off-by: Hillf Danton <hdanton@sina.com> ---