linux-kernel - Re: [PATCH] printk: rename vprintk

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Date:   Tue, 30 Mar 2021 14:32:55 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        John Ogness <john.ogness@...utronix.de>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] printk: rename vprintk_func to vprintk

On Tue 2021-03-23 15:42:01, Rasmus Villemoes wrote:
> The printk code is already hard enough to understand. Remove an
> unnecessary indirection by renaming vprintk_func to vprintk (adding
> the asmlinkage annotation), and removing the vprintk definition from
> printk.c. That way, printk is implemented in terms of vprintk as one
> would expect, and there's no "vprintk_func, what's that? Some function
> pointer that gets set where?"
> 
> The declaration of vprintk in linux/printk.h already has the
> __printf(1,0) attribute, there's no point repeating that with the
> definition - it's for diagnostics in callers.
> 
> linux/printk.h already contains a static inline {return 0;} definition
> of vprintk when !CONFIG_PRINTK.
> 
> Since the corresponding stub definition of vprintk_func was not marked
> "static inline", any translation unit including internal.h would get a
> definition of vprintk_func - it just so happens that for
> !CONFIG_PRINTK, there is precisely one such TU, namely printk.c. Had
> there been more, it would be a link error; now it's just a silly waste
> of a few bytes of .text, which one must assume are rather precious to
> anyone disabling PRINTK.
> 
> $ objdump -dr kernel/printk/printk.o
> 00000330 <vprintk_func>:
>  330:   31 c0                   xor    %eax,%eax
>  332:   c3                      ret
>  333:   8d b4 26 00 00 00 00    lea    0x0(%esi,%eiz,1),%esi
>  33a:   8d b6 00 00 00 00       lea    0x0(%esi),%esi
> 
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>

Nice clean up!

Reviewed-by: Petr Mladek <pmladek@...e.com>

John,

it conflicts with the patchset removing printk safe buffers[1].
Would you prefer to queue this into the patchset?
Or should I push it into printk/linux.git, printk-rework and you would
base v2 on top of it?

Best Regards,
Petr