Received-SPF: pass (google.com: domain of linux-kernel+bounces-74113-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Sender: Tejun Heo <htejun@gmail.com>
Date: Tue, 20 Feb 2024 19:47:00 -1000
From: Tejun Heo <tj@kernel.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
	allen.lkml@gmail.com, kernel-team@meta.com
Subject: Re: [PATCH 12/17] workqueue: Implement disable/enable for (delayed)
 work items
Message-ID: <ZdWOVP5zwD_Uyeoj@slm.duckdns.org>
References: <20240216180559.208276-1-tj@kernel.org>
 <20240216180559.208276-13-tj@kernel.org>
 <CAJhGHyCOgrU9TC9o97LpvAEL2p+Dgt=uN0mo01Gr7HadVSD-Ag@mail.gmail.com>
 <ZdTxisk3zp_eXDVb@slm.duckdns.org>
 <CAJhGHyCvk=uqcjjf-=L64ig2m00qdEuRLSvc0qiJm_SftGqunQ@mail.gmail.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAJhGHyCvk=uqcjjf-=L64ig2m00qdEuRLSvc0qiJm_SftGqunQ@mail.gmail.com>

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