linux-kernel - Re: [PATCH] workqueue: add workqueue.mayday_initial

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Message-ID: <aRSvxyoWiqzcBj-N@slm.duckdns.org>
Date: Wed, 12 Nov 2025 06:03:19 -1000
From: Tejun Heo <tj@...nel.org>
To: ying chen <yc1082463@...il.com>
Cc: corbet@....net, jiangshanlai@...il.com, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, laoar.shao@...il.com
Subject: Re: [PATCH] workqueue: add workqueue.mayday_initial_timeout

Hello,

On Wed, Nov 12, 2025 at 10:01:10AM +0800, ying chen wrote:
> Works that have already been scheduled will be executed sequentially
> within the rescuer thread.
> static int rescuer_thread(void *__rescuer)
> {
>                 ......
>                 /*
>                  * Slurp in all works issued via this workqueue and
>                  * process'em.
>                  */
>                 WARN_ON_ONCE(!list_empty(scheduled));
>                 list_for_each_entry_safe(work, n, &pool->worklist, entry) {
>                         if (get_work_pwq(work) == pwq) {
>                                 if (first)
>                                         pool->watchdog_ts = jiffies;
>                                 move_linked_works(work, scheduled, &n);
>                         }
>                         first = false;
>                 }
> 
>                 if (!list_empty(scheduled)) {
>                         process_scheduled_works(rescuer);
>                         ......
>                 }

Ah, I see what you mean. The slurping is to avoid potentially O(N^2)
scanning but that probably the wrong trade-off to make here. I think the
right solution is making it break out after finding the first matching work
item and loop outside so that it processes work item one by one.

Thanks.

-- 
tejun