linux-kernel - Re: [PATCH printk v1 10/13] printk: add kthread console printers

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Message-ID: <Ygooq5zdsQHJ5Eiy@alley>
Date:   Mon, 14 Feb 2022 11:02:19 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>
Cc:     John Ogness <john.ogness@...utronix.de>,
        Hillf Danton <hdanton@...a.com>, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH printk v1 10/13] printk: add kthread console printers

On Mon 2022-02-14 15:12:51, Sergey Senozhatsky wrote:
> On (22/02/08 15:53), Petr Mladek wrote:
> > My mine concern is that the kthread_worker API still uses an internal
> > lock. And it is yet another layer that might be hard to debug when
> > printk() does not work.
> 
> Isn't this also true for kthreads? Looks like we add "couple of spin_locks"
> to the picture - rq, etc. - one way of the other.

kthread_worker API is built on top of kthreads. It means one more
lock, one more layer to deal with.

If anyone wants to propose workqueues or kthread_worker API, please,
come up with a code and proof that it makes things easier.

It is fine to mention this possibility. It is fine to consider it.
It is fine to keep it in mind. But I do not want to spent too much
time on theoretic discussions at the moment. We have a code now.
John has spent non-trivial time on it. Let's concentrate
on review.

Best Regards,
Petr