linux-kernel - Re: [PATCH v1 4/4] lib/vsprintf: Split out sprintf() and friends

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Date:   Fri, 4 Aug 2023 11:31:58 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Marco Elver <elver@...gle.com>, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-mm@...ck.org
Cc:     Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v1 4/4] lib/vsprintf: Split out sprintf() and friends

On 04/08/2023 10.26, Andy Shevchenko wrote:
> kernel.h is being used as a dump for all kinds of stuff for a long time.
> sprintf() and friends are used in many drivers without need of the full
> kernel.h dependency train with it.
> 
> Here is the attempt on cleaning it up by splitting out sprintf() and
> friends.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  include/linux/kernel.h  | 30 +-----------------------------
>  include/linux/sprintf.h | 24 ++++++++++++++++++++++++
>  lib/vsprintf.c          |  1 +
>  3 files changed, 26 insertions(+), 29 deletions(-)
>  create mode 100644 include/linux/sprintf.h
> 
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index b9e76f717a7e..cee8fe87e9f4 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -29,6 +29,7 @@
>  #include <linux/panic.h>
>  #include <linux/printk.h>
>  #include <linux/build_bug.h>
> +#include <linux/sprintf.h>
>  #include <linux/static_call_types.h>
>  #include <linux/instruction_pointer.h>
>  #include <asm/byteorder.h>
> @@ -203,35 +204,6 @@ static inline void might_fault(void) { }
>  
>  void do_exit(long error_code) __noreturn;
>  
> -extern int num_to_str(char *buf, int size,
> -		      unsigned long long num, unsigned int width);
> -
> -/* lib/printf utilities */
> -
> -extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
> -extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
> -extern __printf(3, 4)
> -int snprintf(char *buf, size_t size, const char *fmt, ...);
> -extern __printf(3, 0)
> -int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
> -extern __printf(3, 4)
> -int scnprintf(char *buf, size_t size, const char *fmt, ...);
> -extern __printf(3, 0)
> -int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
> -extern __printf(2, 3) __malloc
> -char *kasprintf(gfp_t gfp, const char *fmt, ...);
> -extern __printf(2, 0) __malloc
> -char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
> -extern __printf(2, 0)
> -const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args);
> -
> -extern __scanf(2, 3)
> -int sscanf(const char *, const char *, ...);
> -extern __scanf(2, 0)
> -int vsscanf(const char *, const char *, va_list);
> -
> -extern int no_hash_pointers_enable(char *str);
> -
>  extern int get_option(char **str, int *pint);
>  extern char *get_options(const char *str, int nints, int *ints);
>  extern unsigned long long memparse(const char *ptr, char **retptr);
> diff --git a/include/linux/sprintf.h b/include/linux/sprintf.h
> new file mode 100644
> index 000000000000..00d1fdc70a3e
> --- /dev/null
> +++ b/include/linux/sprintf.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_KERNEL_SPRINTF_H_
> +#define _LINUX_KERNEL_SPRINTF_H_
> +
> +#include <linux/types.h>
> +

Shouldn't this at least also include compiler_attributes.h, to make it
self-contained?

As Marco said, please just declare no_hash_pointers in this file as
well. Perhaps with a comment about not accessing it unless one has good
reason, but I suppose that's true in general for all kernel global
variables, so maybe not worth it for this one.

Rasmus