linux-kernel - Re: [PATCH] kgdboc: Disable all the early code when kgdboc is a module

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Message-ID: <20200520103414.bejflo3s4exrcyzk@holly.lan>
Date:   Wed, 20 May 2020 11:34:14 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Jason Wessel <jason.wessel@...driver.com>,
        linux-next@...r.kernel.org, sumit.garg@...aro.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        linux-serial@...r.kernel.org
Subject: Re: [PATCH] kgdboc: Disable all the early code when kgdboc is a
 module

On Tue, May 19, 2020 at 08:44:02AM -0700, Douglas Anderson wrote:
> When kgdboc is compiled as a module all of the "ekgdboc" and
> "kgdb_earlycon" code isn't useful and, in fact, breaks compilation.
> This is because early_param() isn't defined for modules and that's how
> this code gets configured.
> 
> It turns out that this was broken by commit eae3e19ca930 ("kgdboc:
> Remove useless #ifdef CONFIG_KGDB_SERIAL_CONSOLE in kgdboc") and then
> made worse by commit 220995622da5 ("kgdboc: Add kgdboc_earlycon to
> support early kgdb using boot consoles").  I guess the #ifdef wasn't
> so useless, even if it wasn't obvious why it was useful.  When kgdboc
> was compiled as a module only "CONFIG_KGDB_SERIAL_CONSOLE_MODULE" was
> defined, not "CONFIG_KGDB_SERIAL_CONSOLE".  That meant that the old
> module.
> 
> Let's basically do the same thing that the old code (pre-removal of
> the #ifdef) did but use "IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE)" to
> make it more obvious what the point of the check is.  We'll fix
> kgdboc_earlycon in a similar way.
> 
> Fixes: 220995622da5 ("kgdboc: Add kgdboc_earlycon to support early kgdb using boot consoles")
> Fixes: eae3e19ca930 ("kgdboc: Remove useless #ifdef CONFIG_KGDB_SERIAL_CONSOLE in kgdboc")
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>

Applied, thanks!


Daniel.


> ---
> 
>  drivers/tty/serial/kgdboc.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
> index 34b5e91dd245..fa6f7a3e73b9 100644
> --- a/drivers/tty/serial/kgdboc.c
> +++ b/drivers/tty/serial/kgdboc.c
> @@ -43,9 +43,11 @@ static int			kgdb_tty_line;
>  
>  static struct platform_device *kgdboc_pdev;
>  
> +#if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE)
>  static struct kgdb_io		kgdboc_earlycon_io_ops;
>  static struct console		*earlycon;
>  static int                      (*earlycon_orig_exit)(struct console *con);
> +#endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
>  
>  #ifdef CONFIG_KDB_KEYBOARD
>  static int kgdboc_reset_connect(struct input_handler *handler,
> @@ -140,10 +142,19 @@ static void kgdboc_unregister_kbd(void)
>  #define kgdboc_restore_input()
>  #endif /* ! CONFIG_KDB_KEYBOARD */
>  
> -static void cleanup_kgdboc(void)
> +#if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE)
> +static void cleanup_earlycon(void)
>  {
>  	if (earlycon)
>  		kgdb_unregister_io_module(&kgdboc_earlycon_io_ops);
> +}
> +#else /* !IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
> +static inline void cleanup_earlycon(void) { }
> +#endif /* !IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
> +
> +static void cleanup_kgdboc(void)
> +{
> +	cleanup_earlycon();
>  
>  	if (configured != 1)
>  		return;
> @@ -388,6 +399,7 @@ static struct kgdb_io kgdboc_io_ops = {
>  	.post_exception		= kgdboc_post_exp_handler,
>  };
>  
> +#if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE)
>  static int kgdboc_option_setup(char *opt)
>  {
>  	if (!opt) {
> @@ -544,6 +556,7 @@ static int __init kgdboc_earlycon_init(char *opt)
>  }
>  
>  early_param("kgdboc_earlycon", kgdboc_earlycon_init);
> +#endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
>  
>  module_init(init_kgdboc);
>  module_exit(exit_kgdboc);
> -- 
> 2.26.2.761.g0e0b3e54be-goog
>