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

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Message-ID: <87k0po4x1o.fsf@jogness.linutronix.de>
Date:   Tue, 30 Mar 2021 14:59:31 +0200
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
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 2021-03-30, Petr Mladek <pmladek@...e.com> wrote:
> 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?

Please push it to printk-rework. I will base my v2 on top of it.

Thanks.

John