Re: [PATCH 1/2] tracing: work around -Wmissing-format-attribute warning

On Tue, Jun 02, 2026 at 05:07:05PM +0200, Arnd Bergmann wrote:
> 
> A number of tracing headers turn off -Wsuggest-attribute=format for
> gcc, but they don't turn it off for clang, so the same warning still
> happens on new versions of clang that support the format attribute.
> 
> To avoid duplicating the same thing in each tracing header, as well
> as changing all of them to also turn it off for clang, add a new
> __vsnprintf() helper that is not annotated this way in linux/sprintf.h
> but is defined to work the same way as the regular vsprintf.

vsprintf()

> Aside from tracing, the same thing can be used in va_format(),
> which is part of lib/vsprintf.c itself.

...

> --- a/include/linux/sprintf.h
> +++ b/include/linux/sprintf.h
> @@ -12,6 +12,7 @@ __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
>  __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
>  __printf(3, 4) int snprintf(char *buf, size_t size, const char *fmt, ...);
>  __printf(3, 0) int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
> +int __vsnprintf(char *buf, size_t size, const char *fmt, va_list args);

Why the __printf() annotation is in the C file and not here?
Is this all about headers as the second paragraph in the commit message explains?
I would add a comment to explain it here, otherwise we might see false patches to
"make things consistent" in a wrong way.

>  __printf(3, 4) int scnprintf(char *buf, size_t size, const char *fmt, ...);
>  __printf(3, 0) int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
>  __printf(2, 3) __malloc char *kasprintf(gfp_t gfp, const char *fmt, ...);

-- 
With Best Regards,
Andy Shevchenko