linux-kernel - Re: [PATCH 5/9] vdso: Split linux/minmax.h

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Message-ID: <b78eab34-61f5-4c9e-b080-d2524cd30eb8@csgroup.eu>
Date: Wed, 4 Sep 2024 19:17:29 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Vincenzo Frascino <vincenzo.frascino@....com>,
 linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, linux-mm@...ck.org
Cc: Andy Lutomirski <luto@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 "Jason A . Donenfeld" <Jason@...c4.com>,
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
 Naveen N Rao <naveen@...nel.org>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H . Peter Anvin" <hpa@...or.com>, Theodore Ts'o <tytso@....edu>,
 Arnd Bergmann <arnd@...db.de>, Andrew Morton <akpm@...ux-foundation.org>,
 Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH 5/9] vdso: Split linux/minmax.h



Le 03/09/2024 à 17:14, Vincenzo Frascino a écrit :
> The VDSO implementation includes headers from outside of the
> vdso/ namespace.
> 
> Split linux/minmax.h to make sure that the generic library
> uses only the allowed namespace.

It is probably easier to just don't use min_t() in VDSO. Can be open 
coded without impeeding readability.

> 
> Cc: Andy Lutomirski <luto@...nel.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Jason A. Donenfeld <Jason@...c4.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
> ---
>   include/linux/minmax.h | 28 +---------------------------
>   include/vdso/minmax.h  | 38 ++++++++++++++++++++++++++++++++++++++
>   2 files changed, 39 insertions(+), 27 deletions(-)
>   create mode 100644 include/vdso/minmax.h
> 
> diff --git a/include/linux/minmax.h b/include/linux/minmax.h
> index 98008dd92153..846e3fa65c96 100644
> --- a/include/linux/minmax.h
> +++ b/include/linux/minmax.h
> @@ -6,6 +6,7 @@
>   #include <linux/compiler.h>
>   #include <linux/const.h>
>   #include <linux/types.h>
> +#include <vdso/minmax.h>
>   
>   /*
>    * min()/max()/clamp() macros must accomplish three things:
> @@ -84,17 +85,6 @@
>   #define __types_ok3(x,y,z,ux,uy,uz) \
>   	(__sign_use(x,ux) & __sign_use(y,uy) & __sign_use(z,uz))
>   
> -#define __cmp_op_min <
> -#define __cmp_op_max >
> -
> -#define __cmp(op, x, y)	((x) __cmp_op_##op (y) ? (x) : (y))
> -
> -#define __cmp_once_unique(op, type, x, y, ux, uy) \
> -	({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
> -
> -#define __cmp_once(op, type, x, y) \
> -	__cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
> -
>   #define __careful_cmp_once(op, x, y, ux, uy) ({		\
>   	__auto_type ux = (x); __auto_type uy = (y);	\
>   	BUILD_BUG_ON_MSG(!__types_ok(x,y,ux,uy),	\
> @@ -204,22 +194,6 @@
>    * Or not use min/max/clamp at all, of course.
>    */
>   
> -/**
> - * min_t - return minimum of two values, using the specified type
> - * @type: data type to use
> - * @x: first value
> - * @y: second value
> - */
> -#define min_t(type, x, y) __cmp_once(min, type, x, y)
> -
> -/**
> - * max_t - return maximum of two values, using the specified type
> - * @type: data type to use
> - * @x: first value
> - * @y: second value
> - */
> -#define max_t(type, x, y) __cmp_once(max, type, x, y)
> -
>   /*
>    * Do not check the array parameter using __must_be_array().
>    * In the following legit use-case where the "array" passed is a simple pointer,
> diff --git a/include/vdso/minmax.h b/include/vdso/minmax.h
> new file mode 100644
> index 000000000000..26724f34c513
> --- /dev/null
> +++ b/include/vdso/minmax.h
> @@ -0,0 +1,38 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __VDSO_MINMAX_H
> +#define __VDSO_MINMAX_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/compiler.h>
> +
> +#define __cmp_op_min <
> +#define __cmp_op_max >
> +
> +#define __cmp(op, x, y)	((x) __cmp_op_##op (y) ? (x) : (y))
> +
> +#define __cmp_once_unique(op, type, x, y, ux, uy) \
> +	({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
> +
> +#define __cmp_once(op, type, x, y) \
> +	__cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
> +
> +/**
> + * min_t - return minimum of two values, using the specified type
> + * @type: data type to use
> + * @x: first value
> + * @y: second value
> + */
> +#define min_t(type, x, y) __cmp_once(min, type, x, y)
> +
> +/**
> + * max_t - return maximum of two values, using the specified type
> + * @type: data type to use
> + * @x: first value
> + * @y: second value
> + */
> +#define max_t(type, x, y) __cmp_once(max, type, x, y)
> +
> +#endif /* !__ASSEMBLY__ */
> +
> +#endif /* __VDSO_MINMAX_H */