linux-kernel - Re: [RFC PATCH] kthread: do not modify running work

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Message-ID: <877ds9do4f.fsf@nanos.tec.linutronix.de>
Date:   Fri, 02 Oct 2020 10:32:32 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Hillf Danton <hdanton@...a.com>
Cc:     Hillf Danton <hdanton@...a.com>, Petr Mladek <pmladek@...e.com>,
        linux-kernel@...r.kernel.org, tj@...nel.org,
        akpm@...ux-foundation.org, Peter Zijlstra <peterz@...radead.org>,
        Zqiang <qiang.zhang@...driver.com>
Subject: Re: [RFC PATCH] kthread: do not modify running work

On Fri, Oct 02 2020 at 10:34, Hillf Danton wrote:
> On Thu, 01 Oct 2020 15:59:38 +0200 Thomas Gleixner wrote:
>> On Thu, Oct 01 2020 at 17:51, Hillf Danton wrote:
>> Aside of that it's pretty irrelevant whether there is a user at the
>> moment which reschedules work from the callback or not.
>> 
>> It's something which needs to work because its possible from regular
>> work queues as well and makes a lot of sense.
>
> https://lore.kernel.org/lkml/87eemheay8.fsf@nanos.tec.linutronix.de/

That's a completely different thing, really. This adds new functionality
without users and exports it.

kthread work is modeled after workqueue to address specific
needs. delayed work can be rescheduled from the callback and all
variants of timers support rearming the timer from the callback as well.

So having a consistent behaviour accross all these facilities makes
absolutely sense and I don't agree with your sentiment in the changelog
at all.

Just because it does not make sense to you is not a justification for
making stuff inconsistent. You still have not provided a technical
reason why this change is needed.

Thanks,

        tglx