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

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Date:   Fri, 21 Oct 2022 11:55:50 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     John Ogness <john.ogness@...utronix.de>
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 Wed 2022-10-19 17:01:28, John Ogness wrote:
> Replace (console->flags & CON_ENABLED) usage with console_is_enabled().
> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>
> ---
>  arch/m68k/emu/nfcon.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> 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
> @@ -49,7 +49,7 @@ static void nfcon_write(struct console *con, const char *str,
>  static struct tty_driver *nfcon_device(struct console *con, int *index)
>  {
>  	*index = 0;
> -	return (con->flags & CON_ENABLED) ? nfcon_tty_driver : NULL;
> +	return console_is_enabled(con) ? nfcon_tty_driver : NULL;
>  }
>  
>  static struct console nf_console = {
> @@ -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.

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

The replacement is straightforward. Both checks are or might be racy.
Feel free to use:

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr

>  		register_console(&nf_console);
>  
>  	return 0;