linux-kernel - Re: [PATCH] tools/objtool: Copy the __cleanup unused variable fix for older clang

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Message-ID: <20251101164329.GA3250327@ax162>
Date: Sat, 1 Nov 2025 12:43:29 -0400
From: Nathan Chancellor <nathan@...nel.org>
To: Borislav Petkov <bp@...en8.de>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>, linux-kernel@...r.kernel.org,
	linux-tip-commits@...r.kernel.org, Petr Mladek <pmladek@...e.com>,
	Joe Lawrence <joe.lawrence@...hat.com>, x86@...nel.org
Subject: Re: [PATCH] tools/objtool: Copy the __cleanup unused variable fix
 for older clang

On Sat, Nov 01, 2025 at 01:44:32PM +0100, Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@...en8.de>
> Date: Sat, 1 Nov 2025 13:37:51 +0100
> 
> Copy from
> 
>   54da6a092431 ("locking: Introduce __cleanup() based infrastructure")
> 
> the bits which mark the variable with a cleanup attribute unused so that my
> clang 15 can dispose of it properly instead of warning that it is unused which
> then fails the build due to -Werror.
> 
> Suggested-by: Nathan Chancellor <nathan@...nel.org>
> Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
> Link: https://lore.kernel.org/r/20251031114919.GBaQSiPxZrziOs3RCW@fat_crate.local

Reviewed-by: Nathan Chancellor <nathan@...nel.org>

> ---
>  tools/objtool/include/objtool/warn.h | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
> index e88322d97573..a1e3927d8e7c 100644
> --- a/tools/objtool/include/objtool/warn.h
> +++ b/tools/objtool/include/objtool/warn.h
> @@ -107,6 +107,15 @@ extern int indent;
>  
>  static inline void unindent(int *unused) { indent--; }
>  
> +/*
> + * Clang prior to 17 is being silly and considers many __cleanup() variables
> + * as unused (because they are, their sole purpose is to go out of scope).
> + *
> + * https://github.com/llvm/llvm-project/commit/877210faa447f4cc7db87812f8ed80e398fedd61
> + */
> +#undef __cleanup
> +#define __cleanup(func) __maybe_unused __attribute__((__cleanup__(func)))
> +
>  #define __dbg(format, ...)						\
>  	fprintf(stderr,							\
>  		"DEBUG: %s%s" format "\n",				\
> @@ -127,7 +136,7 @@ static inline void unindent(int *unused) { indent--; }
>  })
>  
>  #define dbg_indent(args...)						\
> -	int __attribute__((cleanup(unindent))) __dummy_##__COUNTER__;	\
> +	int __cleanup(unindent) __dummy_##__COUNTER__;			\
>  	__dbg_indent(args);						\
>  	indent++
>  
> -- 
> 2.51.0
> 
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette