linux-kernel - Re: [PATCH v2] printk/console: Enable console kthreads only when there is no boot console left

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Message-ID: <CAFr9PXkKCf-JRcv+bk17HcC8-4kRG=J9bnNtp_nsMqzg4f=epw@mail.gmail.com>
Date:   Tue, 21 Jun 2022 20:42:02 +0900
From:   Daniel Palmer <daniel@...f.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     John Ogness <john.ogness@...utronix.de>,
        Marek Behún <kabel@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Jan Kara <jack@...e.cz>, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v2] printk/console: Enable console kthreads only when
 there is no boot console left

Hi Petr,

On Tue, 21 Jun 2022 at 18:09, Petr Mladek <pmladek@...e.com> wrote:
>
> Threaded console printing does not take into consideration that boot
> consoles may be accessing the same hardware as normal consoles and thus
> must not be called in parallel.
>
> Since it is currently not possible to identify which consoles are
> accessing the same hardware, delay threaded console printing activation
> until it is known that there are no boot consoles registered.
>
> Link: https://lore.kernel.org/r/20220619204949.50d9154d@thinkpad
> Link: https://lore.kernel.org/r/2a82eae7-a256-f70c-fd82-4e510750906e@samsung.com
> Link: https://lore.kernel.org/r/20220619204949.50d9154d@thinkpad
> Reported-by: Marek Behún <kabel@...nel.org>
> [john.ogness@...utronix.de: Better description of the problem.]
> Signed-off-by: Petr Mladek <pmladek@...e.com>
> Tested-by: Marek Behún <kabel@...nel.org>
> ---
> Changes against v1:

The lockups on boot seem to be gone on my boards with this patch.
So FWIW:

Tested-by: Daniel Palmer<daniel@...ngy.jp>