From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Tejun Heo <tj@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Matt Porter <mporter@kernel.crashing.org>,
Alexandre Bounine <alex.bou9@gmail.com>,
Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v3] rapidio/tsi721: Replace flush_scheduled_work() with flush_work().
Date: Tue, 27 Sep 2022 07:13:59 +0900 [thread overview]
Message-ID: <14c0f611-3f21-01b0-88d6-05eb1a3d8bc4@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <YzG/664Z5XqLD/yM@rowland.harvard.edu>
On 2022/09/27 0:06, Alan Stern wrote:
>> Alan Stern suggested to use cancel_work_sync() in
>> commit eef6a7d5c2f38ada ("workqueue: warn about flush_scheduled_work()")
>> and Tejun Heo suggested to use flush_work() in
>> https://lkml.kernel.org/r/YjivtdkpY+reW0Gt@slm.duckdns.org .
>>
>> Is there some reason to prefer one over the other?
>> I think that user-visible results between flush_work() and cancel_work_sync()
>> are the same because both wait until work completes.
>
> No, you haven't got it quite right. flush_work() waits until the work
> completes, but cancel_work_sync() first tries to cancel the work item.
> It then waits until the work item is either cancelled or completed.
I know there is a difference if the cancellation was successful.
But unless cancel_work_sync() is called immediately after schedule_work(),
that work likely (e.g. 99%+) already started running or already completed.
>
> If the cancellation is successful (i.e., it happens before the work item
> starts to run) then the call will return at that time and the work item
> will never run -- hence it will never complete.
A difficult to judge thing is whether the owner/maintainer of that code wants
that work completed or cancelled.
Unlike e.g. https://lkml.kernel.org/r/Yy3byxFrfAfQL9xK@intel.com ,
tsi721_remove() does not say whether pending works should run.
next prev parent reply other threads:[~2022-09-26 22:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-24 5:11 [PATCH v3] rapidio/tsi721: Replace flush_scheduled_work() with flush_work() Tetsuo Handa
2022-09-25 17:27 ` Andrew Morton
2022-09-26 10:28 ` Tetsuo Handa
2022-09-26 15:06 ` Alan Stern
2022-09-26 22:13 ` Tetsuo Handa [this message]
2022-10-10 10:16 ` Tetsuo Handa
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=14c0f611-3f21-01b0-88d6-05eb1a3d8bc4@I-love.SAKURA.ne.jp \
--to=penguin-kernel@i-love.sakura.ne.jp \
--cc=akpm@linux-foundation.org \
--cc=alex.bou9@gmail.com \
--cc=arnd@arndb.de \
--cc=christophe.jaillet@wanadoo.fr \
--cc=linux-kernel@vger.kernel.org \
--cc=mporter@kernel.crashing.org \
--cc=stern@rowland.harvard.edu \
--cc=tj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.