linux-kernel - Re: [PATCH RESEND] printk: report boot console names during cut-over

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 21 Sep 2013 18:52:26 -0500
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joe Perches <joe@...ches.com>, Tejun Heo <tj@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH RESEND] printk: report boot console names during cut-over

On Fri, Sep 20, 2013 at 08:34:01AM -0700, Kees Cook wrote:
> This reports the names of boot consoles as they're being disabled to
> help identify which is which during cut-over. Helps answer the question
> "which boot console actually got activated?" once the regular console
> is running, mostly when debugging boot console failures.
> 
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>  kernel/printk/printk.c |   16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index b4e8500..0dc54c9 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2361,14 +2361,18 @@ void register_console(struct console *newcon)
>  	if (bcon &&
>  	    ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
>  	    !keep_bootcon) {
> -		/* we need to iterate through twice, to make sure we print
> -		 * everything out, before we unregister the console(s)
> +		/* We need to iterate through all boot consoles, to make
> +		 * sure we print everything out, before we unregister them.
>  		 */
> -		printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
> -			newcon->name, newcon->index);
> -		for_each_console(bcon)
> -			if (bcon->flags & CON_BOOT)
> +		for_each_console(bcon) {
> +			if (bcon->flags & CON_BOOT) {
> +				printk(KERN_INFO "console [%s%d] enabled, "
> +					"bootconsole [%s%d] disabled\n",
> +					newcon->name, newcon->index,
> +					bcon->name, bcon->index);
>  				unregister_console(bcon);

Looks useful! But I think the "console %foo disabled" message should move to unregister_console()
instead. That way it also handles printk_late_init() and all other console unregisters.

Thanks.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/