linux-kernel - Re: [PATCH printk v2 06/38] tty: nfcon: use console_is

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Message-ID: <87fsf49e6d.fsf@jogness.linutronix.de>
Date:   Mon, 31 Oct 2022 17:05:54 +0106
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,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org
Subject: Re: [PATCH printk v2 06/38] tty: nfcon: use console_is_enabled()

On 2022-10-21, Petr Mladek <pmladek@...e.com> wrote:
>> diff --git a/arch/m68k/emu/nfcon.c b/arch/m68k/emu/nfcon.c
>> index 557d60867f98..c542fc2b121f 100644
>> --- a/arch/m68k/emu/nfcon.c
>> +++ b/arch/m68k/emu/nfcon.c
>> @@ -151,7 +151,7 @@ static int __init nfcon_init(void)
>>  
>>  	nfcon_tty_driver = driver;
>>  
>> -	if (!(nf_console.flags & CON_ENABLED))
>> +	if (!console_is_enabled(&nf_console))
>
> Heh, the check of CON_ENABLED does not make much sense. IMHO, the
> important thing is whether the console is in console_list or not.
>
> I would personally add a check at the beginning of register_console()
> whether the console is already registered and enabled() and do
> nothing when already done.

Actually, register_console() already has this check, but it does a
WARN(). If the debug setup is used for nfcon, this situation is
normal. So probably to avoid the WARN, the CON_ENABLED code was added.

> I would be nice to fix this. But it might be done later.

I could add a console_is_registered() function that checks if the
console is in the console list and use that instead. If we are going to
touch this code, we might as well touch it correctly, right?

John