linux-kernel - Re: [PATCH printk v5 37/40] tty: serial: kgdboc: synchronize tty_find_polling_driver() and register

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Message-ID: <87pmdloq7r.fsf@jogness.linutronix.de>
Date:   Thu, 17 Nov 2022 11:06:40 +0106
From:   John Ogness <john.ogness@...utronix.de>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Jason Wessel <jason.wessel@...driver.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        kgdb-bugreport@...ts.sourceforge.net, linux-serial@...r.kernel.org
Subject: Re: [PATCH printk v5 37/40] tty: serial: kgdboc: synchronize
 tty_find_polling_driver() and register_console()

On 2022-11-16, Doug Anderson <dianders@...omium.org> wrote:
> Seems OK to me, though I guess I would have moved console_lock() up
> too just because this isn't a case we need to optimize and then we can
> be extra certain that nobody else is messing with console structures
> while we're looking at them.

Actually this series is not about optimization. It is about reducing the
scope of console_lock and removing unnecessary use of it.

If tty_find_polling_driver() needs to be called under the console_lock,
then we need to document exactly why. I could not find any situations
where it is necessary.

Also keep in mind that in the long term we will be completely removing
the console_lock. It is a painful process of identifying and dismantling
its scope and replacing it with multiple clearly scoped locking
mechanisms.

> Reviewed-by: Douglas Anderson <dianders@...omium.org>

Thanks.

John