netdev - Re: [PATCH printk v2 09/38] netconsole: use console_is

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Date:   Fri, 21 Oct 2022 15:14:59 +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,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: Re: [PATCH printk v2 09/38] netconsole: use console_is_enabled()

On Wed 2022-10-19 17:01:31, John Ogness wrote:
> Replace (console->flags & CON_ENABLED) usage with console_is_enabled().
> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

The change is straightforward:

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

The comment below is just a lamentation about the netconsole code.

> ---
>  drivers/net/netconsole.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
> index bdff9ac5056d..073e59a06f21 100644
> --- a/drivers/net/netconsole.c
> +++ b/drivers/net/netconsole.c
> @@ -332,7 +332,7 @@ static ssize_t enabled_store(struct config_item *item,
>  	}
>  
>  	if (enabled) {	/* true */
> -		if (nt->extended && !(netconsole_ext.flags & CON_ENABLED)) {
> +		if (nt->extended && !console_is_enabled(&netconsole_ext)) {
>  			netconsole_ext.flags |= CON_ENABLED;
>  			register_console(&netconsole_ext);
>  		}
> @@ -915,7 +915,7 @@ static int __init init_netconsole(void)
>  	if (err)
>  		goto undonotifier;
>  
> -	if (netconsole_ext.flags & CON_ENABLED)
> +	if (console_is_enabled(&netconsole_ext))
>  		register_console(&netconsole_ext);
>  	register_console(&netconsole);
>  	pr_info("network logging started\n");

Just for record:

This looks like a (mis)use of CON_ENABLED flag. It took me some time
to understand why pre-enabled consoles are handled special way in
register_console(). I partly documented it in
try_enable_preferred_console():

	/*
	 * Some consoles, such as pstore and netconsole, can be enabled even
	 * without matching. Accept the pre-enabled consoles only when match()
	 * and setup() had a chance to be called.
	 */
	if (console_is_enabled(newcon) && (c->user_specified == user_specified))
		return 0;

In my bottom driver, I have a patch cleaning this. It is part of a bigger
clean up that is not ready for upstream :-/

Best Regards,
Petr