linux-kernel - Re: [PATCH 12/17] workqueue: Implement disable/enable for (delayed) work items

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Date: Tue, 20 Feb 2024 19:47:00 -1000
From: Tejun Heo <tj@...nel.org>
To: Lai Jiangshan <jiangshanlai@...il.com>
Cc: torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	allen.lkml@...il.com, kernel-team@...a.com
Subject: Re: [PATCH 12/17] workqueue: Implement disable/enable for (delayed)
 work items

Hello,

On Wed, Feb 21, 2024 at 10:54:46AM +0800, Lai Jiangshan wrote:
> I think it is better to have the same handling (checking disable count)
> in queue_rcu_work().
> 
> 1) code is consistent with other queuing code
> 2) known state: no work item is queued with disable count > 0
> 3) catch wrong usages: some complaining code can be added when adding the check.
> 
> Adding checking and complaining in the code is as important as
> adding a comment stating rcu work is not allowed to be disabled/canceled.

Sure, will add a WARN_ON_ONCE().

> > I'm not quite sure flush_delayed_work() is safe. Will think more about that.
> 
> I think the code successfully deleting the timer not only owns the pending bit
> but also ensures the disable count is zero.

Yeah, this should be fine.

Thanks.

-- 
tejun