linux-kernel - Re: [PATCH 4/7] drivers: serial: kgdboc: Check CON_SUSPENDED instead of CON

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Message-ID: <CAD=FV=XXQyZLYKoszj68ZGFDY=9-cmEUp406WeOeSBVZOHyUHw@mail.gmail.com>
Date: Mon, 9 Jun 2025 13:13:21 -0700
From: Doug Anderson <dianders@...omium.org>
To: Marcos Paulo de Souza <mpdesouza@...e.com>
Cc: Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>, 
	John Ogness <john.ogness@...utronix.de>, Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Jason Wessel <jason.wessel@...driver.com>, Daniel Thompson <danielt@...nel.org>, 
	Richard Weinberger <richard@....at>, Anton Ivanov <anton.ivanov@...bridgegreys.com>, 
	Johannes Berg <johannes@...solutions.net>, linux-kernel@...r.kernel.org, 
	linux-serial@...r.kernel.org, kgdb-bugreport@...ts.sourceforge.net, 
	linux-um@...ts.infradead.org
Subject: Re: [PATCH 4/7] drivers: serial: kgdboc: Check CON_SUSPENDED instead
 of CON_ENABLED

Hi,

On Fri, Jun 6, 2025 at 7:54 PM Marcos Paulo de Souza <mpdesouza@...e.com> wrote:
>
> All consoles found on for_each_console are registered, meaning that all of
> them are CON_ENABLED. The code tries to find an active console, so check if the
> console is not suspended instead.
>
> Signed-off-by: Marcos Paulo de Souza <mpdesouza@...e.com>
> ---
>  drivers/tty/serial/kgdboc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
> index 85f6c5a76e0fff556f86f0d45ebc5aadf5b191e8..af6d2208b8ddb82d62f33292b006b2923583a0d2 100644
> --- a/drivers/tty/serial/kgdboc.c
> +++ b/drivers/tty/serial/kgdboc.c
> @@ -577,7 +577,8 @@ static int __init kgdboc_earlycon_init(char *opt)
>         console_list_lock();
>         for_each_console(con) {
>                 if (con->write && con->read &&
> -                   (con->flags & (CON_BOOT | CON_ENABLED)) &&
> +                   (con->flags & CON_BOOT) &&
> +                   ((con->flags & CON_SUSPENDED) == 0) &&

I haven't tried running the code, so I could easily be mistaken, but...

...the above doesn't seem like the correct conversion. The old expression was:

(con->flags & (CON_BOOT | CON_ENABLED))

That would evaluate to non-zero (true) if the console was _either_
"boot" or "enabled".

The new expression is is:

(con->flags & CON_BOOT) && ((con->flags & CON_SUSPENDED) == 0)

That's only true if the console is _both_ "boot" and "not suspended".

-Doug