linux-kernel - Re: [PATCH v11 02/21] printk: Make vprintk

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Message-ID: <eacbe956f6815bccd4110cf3f82ffe76c0c4e09b.camel@redhat.com>
Date: Wed, 09 Jul 2025 18:02:23 +0200
From: Gabriele Monaco <gmonaco@...hat.com>
To: Nam Cao <namcao@...utronix.de>, Steven Rostedt <rostedt@...dmis.org>, 
 Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, 	linux-trace-kernel@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: john.ogness@...utronix.de, Petr Mladek <pmladek@...e.com>, Sergey
 Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH v11 02/21] printk: Make vprintk_deferred() public

On Fri, 2025-07-04 at 15:19 +0200, Nam Cao wrote:
> vprintk_deferred() is useful for implementing runtime verification
> reactors. Make it public.
> 
> Signed-off-by: Nam Cao <namcao@...utronix.de>
> Reviewed-by: Petr Mladek <pmladek@...e.com>
> ---
>  include/linux/printk.h   | 5 +++++
>  kernel/printk/internal.h | 1 -
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/printk.h b/include/linux/printk.h
> index 5b462029d03c..08f1775c60fd 100644
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -154,6 +154,7 @@ int vprintk_emit(int facility, int level,
>  
>  asmlinkage __printf(1, 0)
>  int vprintk(const char *fmt, va_list args);
> +__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
>  
>  asmlinkage __printf(1, 2) __cold
>  int _printk(const char *fmt, ...);
> @@ -214,6 +215,10 @@ int vprintk(const char *s, va_list args)
>  {
>  	return 0;
>  }
> +__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args)
> +{
> +	return 0;
> +}

Was just running tests after rebasing and I received a kernel bot
warning from an unlikely build without CONFIG_PRINTK [1].

>> include/linux/printk.h:218:20: warning: no previous prototype for
function 'vprintk_deferred' [-Wmissing-prototypes]
     218 | __printf(1, 0) int vprintk_deferred(const char *fmt, va_list
args)
         |                    ^
   include/linux/printk.h:218:16: note: declare 'static' if the
function is not intended to be used outside of this translation unit
     218 | __printf(1, 0) int vprintk_deferred(const char *fmt, va_list
args)
         |                ^
         |                static
   1 warning generated.


I believe this ought to be static:

+static inline __printf(1, 0) int vprintk_deferred(const char *fmt,
+						   va_list args)
+{
+	return 0;
+}

Cheers,
Gabriele

[1] -
https://download.01.org/0day-ci/archive/20250709/202507092300.Isx1ydMp-lkp@intel.com/

>  static inline __printf(1, 2) __cold
>  int _printk(const char *s, ...)
>  {
> diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
> index 48a24e7b309d..bbed41ad29cf 100644
> --- a/kernel/printk/internal.h
> +++ b/kernel/printk/internal.h
> @@ -72,7 +72,6 @@ int vprintk_store(int facility, int level,
>  		  const char *fmt, va_list args);
>  
>  __printf(1, 0) int vprintk_default(const char *fmt, va_list args);
> -__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
>  
>  void __printk_safe_enter(void);
>  void __printk_safe_exit(void);