linux-kernel - Re: [PATCH printk v2 38/38] printk, xen: fbfront: create/use safe function for forcing preferred

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Date:   Thu, 27 Oct 2022 15:41:23 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Helge Deller <deller@....de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Tom Rix <trix@...hat.com>, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH printk v2 38/38] printk, xen: fbfront: create/use safe
 function for forcing preferred

On 2022-10-27, Petr Mladek <pmladek@...e.com> wrote:
>> -	if (c) {
>> -		unregister_console(c);
>> -		c->flags |= CON_CONSDEV;
>> -		c->flags &= ~CON_PRINTBUFFER; /* don't print again */
>> -		register_console(c);
>> -	}
>> +	if (c)
>> +		console_force_preferred(c);
>
> I would prefer to fix this a clean way.
>
> [...]
>
> I would suggest to implement:
>
> [...]
>
> It is a more code. But it is race-free. Also it is much more clear
> what is going on.
>
> How does this sound, please?

I wasn't sure if any of the other preferred-console magic in
register_console() was needed, which is why I kept a full
register_console() call. But if it really is just about forcing it the
head and setting a new CON_CONSDEV, then your suggestion is much
simpler. Thanks.

John