* [RFC] workqueue: fix detecting reentrance
@ 2019-12-12 9:15 Hillf Danton
2019-12-16 14:02 ` Michal Hocko
0 siblings, 1 reply; 2+ messages in thread
From: Hillf Danton @ 2019-12-12 9:15 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-mm, Hillf Danton
If we can find a valid worker that is serving the specified work at
the moment then the worker itself is enough to ensure reentrance and
workqueue doesn't matter here because it is permitted for a work to
requeue itself either on different cpu or numa node or even on another
workqueue.
Fixes: c9178087acd7 ("workqueue: perform non-reentrancy test when queueing to unbound workqueues too")
Fixes: 18aa9effad4a ("workqueue: implement WQ_NON_REENTRANT")
Signed-off-by: Hillf Danton <hdanton@sina.com>
---
--- f/kernel/workqueue.c
+++ g/kernel/workqueue.c
@@ -1433,7 +1433,7 @@ retry:
worker = find_worker_executing_work(last_pool, work);
- if (worker && worker->current_pwq->wq == wq) {
+ if (worker) {
pwq = worker->current_pwq;
} else {
/* meh... not running there, queue here */
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [RFC] workqueue: fix detecting reentrance
2019-12-12 9:15 [RFC] workqueue: fix detecting reentrance Hillf Danton
@ 2019-12-16 14:02 ` Michal Hocko
0 siblings, 0 replies; 2+ messages in thread
From: Michal Hocko @ 2019-12-16 14:02 UTC (permalink / raw)
To: Hillf Danton; +Cc: linux-kernel, linux-mm, Tejun Heo, Lai Jiangshan
Cc maintainers.
On Thu 12-12-19 17:15:48, Hillf Danton wrote:
>
> If we can find a valid worker that is serving the specified work at
> the moment then the worker itself is enough to ensure reentrance and
> workqueue doesn't matter here because it is permitted for a work to
> requeue itself either on different cpu or numa node or even on another
> workqueue.
I do not follow what is the actual problem you are trying to fix here.
> Fixes: c9178087acd7 ("workqueue: perform non-reentrancy test when queueing to unbound workqueues too")
> Fixes: 18aa9effad4a ("workqueue: implement WQ_NON_REENTRANT")
> Signed-off-by: Hillf Danton <hdanton@sina.com>
> ---
>
> --- f/kernel/workqueue.c
> +++ g/kernel/workqueue.c
> @@ -1433,7 +1433,7 @@ retry:
>
> worker = find_worker_executing_work(last_pool, work);
>
> - if (worker && worker->current_pwq->wq == wq) {
> + if (worker) {
> pwq = worker->current_pwq;
> } else {
> /* meh... not running there, queue here */
>
--
Michal Hocko
SUSE Labs
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