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References: <20220924000454.3319186-1-john.ogness@linutronix.de> <20220924000454.3319186-10-john.ogness@linutronix.de>
In-Reply-To: <20220924000454.3319186-10-john.ogness@linutronix.de>
From:   Doug Anderson <dianders@chromium.org>
Date:   Wed, 28 Sep 2022 16:32:51 -0700
Message-ID: <CAD=FV=W5mnR6MH+KLK9VgUCvY0rsjkMdR7un=pHmtNBBup7w7g@mail.gmail.com>
Subject: Re: [PATCH printk 09/18] serial: kgdboc: Lock console list in probe function
To:     John Ogness <john.ogness@linutronix.de>
Cc:     Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>,
        Jason Wessel <jason.wessel@windriver.com>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        kgdb-bugreport@lists.sourceforge.net, linux-serial@vger.kernel.org
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Precedence: bulk

Hi,

On Fri, Sep 23, 2022 at 5:05 PM John Ogness <john.ogness@linutronix.de> wrote:
>
> From: Thomas Gleixner <tglx@linutronix.de>
>
> Unprotected list walks are not necessarily safe.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> ---
>  drivers/tty/serial/kgdboc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
> index 79b7db8580e0..af2aa76bae15 100644
> --- a/drivers/tty/serial/kgdboc.c
> +++ b/drivers/tty/serial/kgdboc.c
> @@ -193,7 +193,8 @@ static int configure_kgdboc(void)
>         if (!p)
>                 goto noconfig;
>
> -       for_each_console(cons) {
> +       console_list_lock();
> +       for_each_registered_console(cons) {
>                 int idx;
>                 if (cons->device && cons->device(cons, &idx) == p &&
>                     idx == tty_line) {
> @@ -201,6 +202,7 @@ static int configure_kgdboc(void)
>                         break;
>                 }
>         }
> +       console_list_unlock();

Seems right to me, thanks!

Reviewed-by: Douglas Anderson <dianders@chromium.org>