From nobody Sat Feb 7 23:06:25 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18664C001DB for ; Fri, 4 Aug 2023 10:56:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230257AbjHDK4m convert rfc822-to-8bit (ORCPT ); Fri, 4 Aug 2023 06:56:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231185AbjHDK4T (ORCPT ); Fri, 4 Aug 2023 06:56:19 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 690896A7D for ; Fri, 4 Aug 2023 03:53:52 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-317-u60WpdTSM-qAirDp1yuD6g-1; Fri, 04 Aug 2023 11:53:35 +0100 X-MC-Unique: u60WpdTSM-qAirDp1yuD6g-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Fri, 4 Aug 2023 11:53:33 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Fri, 4 Aug 2023 11:53:33 +0100 From: David Laight To: "'linux-kernel@vger.kernel.org'" , "'Andy Shevchenko'" , 'Andrew Morton' , "'Matthew Wilcox (Oracle)'" , 'Christoph Hellwig' , "'Jason A. Donenfeld'" , 'Linus Torvalds' Subject: [PATCH v3 1/5] minmax: Add min_unsigned(a, b) and max_unsigned(a, b) Thread-Topic: [PATCH v3 1/5] minmax: Add min_unsigned(a, b) and max_unsigned(a, b) Thread-Index: AdnGwea6QKJE/BTwROarSQggyisG+w== Date: Fri, 4 Aug 2023 10:53:33 +0000 Message-ID: References: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> In-Reply-To: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" These can be used when min()/max() errors a signed v unsigned compare when the signed value is known to be non-negative. Unlike min_t(some_unsigned_type, a, b) min_unsigned() will never mask off high bits if an inappropriate type is selected. The '+ 0u + 0ul + 0ull' may look strange. The '+ 0u' is needed for 'signed int' on 64bit systems. The '+ 0ul' is needed for 'signed long' on 32bit systems. The '+ 0ull' is needed for 'signed long long'. Signed-off-by: David Laight --- v3: No change. v2: Updated commit message. include/linux/minmax.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 396df1121bff..531860e9cc55 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -73,6 +73,23 @@ */ #define max(x, y) __careful_cmp(x, y, >) =20 +/** + * min_unsigned - return minimum of two non-negative values + * Signed types are zero extended to match a larger unsigned type. + * @x: first value + * @y: second value + */ +#define min_unsigned(x, y) \ + __careful_cmp((x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull, <) + +/** + * max_unsigned - return maximum of two non-negative values + * @x: first value + * @y: second value + */ +#define max_unsigned(x, y) \ + __careful_cmp((x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull, >) + /** * min3 - return minimum of three values * @x: first value --=20 2.17.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales) From nobody Sat Feb 7 23:06:25 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06FABC001DB for ; Fri, 4 Aug 2023 10:57:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231646AbjHDK5J convert rfc822-to-8bit (ORCPT ); Fri, 4 Aug 2023 06:57:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231387AbjHDK4m (ORCPT ); Fri, 4 Aug 2023 06:56:42 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9DBCD46BB for ; Fri, 4 Aug 2023 03:54:31 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-209-gl72SDQqNaSwQKmyLPhKNg-1; Fri, 04 Aug 2023 11:54:25 +0100 X-MC-Unique: gl72SDQqNaSwQKmyLPhKNg-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Fri, 4 Aug 2023 11:54:23 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Fri, 4 Aug 2023 11:54:23 +0100 From: David Laight To: "'linux-kernel@vger.kernel.org'" , "'Andy Shevchenko'" , 'Andrew Morton' , "'Matthew Wilcox (Oracle)'" , 'Christoph Hellwig' , "'Jason A. Donenfeld'" , 'Linus Torvalds' Subject: [PATCH v3 2/5] minmax: Allow min()/max()/clamp() if the arguments have the same signedness. Thread-Topic: [PATCH v3 2/5] minmax: Allow min()/max()/clamp() if the arguments have the same signedness. Thread-Index: AdnGwgTiHuP1P74HQhq3IRxkF0FtQw== Date: Fri, 4 Aug 2023 10:54:23 +0000 Message-ID: <6228a4ff9c074075bf07cca0e9d3eab2@AcuMS.aculab.com> References: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> In-Reply-To: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The type-check in min()/max() is there to stop unexpected results if a negative value gets converted to a large unsigned value. However it also rejects 'unsigned int' v 'unsigned long' compares which are common and never problematc. Replace the 'same type' check with a 'same signedness' check. The new test isn't itself a compile time error, so use static_assert() to report the error and give a meaningful error message. Due to the way builtin_choose_expr() works detecting the error in the 'non-constant' side (where static_assert() can be used) also detects errors when the arguments are constant. Signed-off-by: David Laight --- Changes for v3: - Wrap is_signed_type() in __builtin_choose_expr() and __is_constexpr(). Generates a compile-time 0 for pointer types avoiding a bug in clang < 16. Changes for v2: - #include to fix 'um' build. This matches a separate commit from Andy. - Do not delete __typecheck() - used outside this file. - Use __builtin_choose_expr() in __clamp_once() to fix clang builds. include/linux/minmax.h | 65 +++++++++++++++++++++++------------------- 1 file changed, 35 insertions(+), 30 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 531860e9cc55..6f79e44aad86 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -2,6 +2,7 @@ #ifndef _LINUX_MINMAX_H #define _LINUX_MINMAX_H =20 +#include #include =20 /* @@ -9,9 +10,8 @@ * * - avoid multiple evaluations of the arguments (so side-effects like * "x++" happen only once) when non-constant. - * - perform strict type-checking (to generate warnings instead of - * nasty runtime surprises). See the "unnecessary" pointer comparison - * in __typecheck(). + * - perform signed v unsigned type-checking (to generate compile + * errors instead of nasty runtime surprises). * - retain result as a constant expressions when called with only * constant expressions (to avoid tripping VLA warnings in stack * allocation usage). @@ -19,23 +19,30 @@ #define __typecheck(x, y) \ (!!(sizeof((typeof(x) *)1 =3D=3D (typeof(y) *)1))) =20 -#define __no_side_effects(x, y) \ - (__is_constexpr(x) && __is_constexpr(y)) +/* is_signed_type() isn't a constexpr for pointer types */ +#define __is_signed(x) \ + __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \ + is_signed_type(typeof(x)), 0) =20 -#define __safe_cmp(x, y) \ - (__typecheck(x, y) && __no_side_effects(x, y)) +#define __types_ok(x, y) \ + (__is_signed(x) =3D=3D __is_signed(y)) =20 -#define __cmp(x, y, op) ((x) op (y) ? (x) : (y)) +#define __cmp_op_min < +#define __cmp_op_max > =20 -#define __cmp_once(x, y, unique_x, unique_y, op) ({ \ +#define __cmp(op, x, y) ((x) __cmp_op_##op (y) ? (x) : (y)) + +#define __cmp_once(op, x, y, unique_x, unique_y) ({ \ typeof(x) unique_x =3D (x); \ typeof(y) unique_y =3D (y); \ - __cmp(unique_x, unique_y, op); }) + static_assert(__types_ok(x, y), \ + #op "(" #x ", " #y ") signedness error, fix types or consider " #op "_u= nsigned() before " #op "_t()"); \ + __cmp(op, unique_x, unique_y); }) =20 -#define __careful_cmp(x, y, op) \ - __builtin_choose_expr(__safe_cmp(x, y), \ - __cmp(x, y, op), \ - __cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op)) +#define __careful_cmp(op, x, y) \ + __builtin_choose_expr(__is_constexpr((x) - (y)), \ + __cmp(op, x, y), \ + __cmp_once(op, x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y))) =20 #define __clamp(val, lo, hi) \ ((val) >=3D (hi) ? (hi) : ((val) <=3D (lo) ? (lo) : (val))) @@ -44,17 +51,15 @@ typeof(val) unique_val =3D (val); \ typeof(lo) unique_lo =3D (lo); \ typeof(hi) unique_hi =3D (hi); \ + static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), \ + (lo) <=3D (hi), true), \ + "clamp() low limit " #lo " greater than high limit " #hi); \ + static_assert(__types_ok(val, lo), "clamp() 'lo' signedness error"); \ + static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error"); \ __clamp(unique_val, unique_lo, unique_hi); }) =20 -#define __clamp_input_check(lo, hi) \ - (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \ - __is_constexpr((lo) > (hi)), (lo) > (hi), false))) - #define __careful_clamp(val, lo, hi) ({ \ - __clamp_input_check(lo, hi) + \ - __builtin_choose_expr(__typecheck(val, lo) && __typecheck(val, hi) && \ - __typecheck(hi, lo) && __is_constexpr(val) && \ - __is_constexpr(lo) && __is_constexpr(hi), \ + __builtin_choose_expr(__is_constexpr((val) - (lo) + (hi)), \ __clamp(val, lo, hi), \ __clamp_once(val, lo, hi, __UNIQUE_ID(__val), \ __UNIQUE_ID(__lo), __UNIQUE_ID(__hi))); }) @@ -64,14 +69,14 @@ * @x: first value * @y: second value */ -#define min(x, y) __careful_cmp(x, y, <) +#define min(x, y) __careful_cmp(min, x, y) =20 /** * max - return maximum of two values of the same or compatible types * @x: first value * @y: second value */ -#define max(x, y) __careful_cmp(x, y, >) +#define max(x, y) __careful_cmp(max, x, y) =20 /** * min_unsigned - return minimum of two non-negative values @@ -79,16 +84,16 @@ * @x: first value * @y: second value */ -#define min_unsigned(x, y) \ - __careful_cmp((x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull, <) +#define min_unsigned(x, y) \ + __careful_cmp(min, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull) =20 /** * max_unsigned - return maximum of two non-negative values * @x: first value * @y: second value */ -#define max_unsigned(x, y) \ - __careful_cmp((x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull, >) +#define max_unsigned(x, y) \ + __careful_cmp(max, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull) =20 /** * min3 - return minimum of three values @@ -140,7 +145,7 @@ * @x: first value * @y: second value */ -#define min_t(type, x, y) __careful_cmp((type)(x), (type)(y), <) +#define min_t(type, x, y) __careful_cmp(min, (type)(x), (type)(y)) =20 /** * max_t - return maximum of two values, using the specified type @@ -148,7 +153,7 @@ * @x: first value * @y: second value */ -#define max_t(type, x, y) __careful_cmp((type)(x), (type)(y), >) +#define max_t(type, x, y) __careful_cmp(max, (type)(x), (type)(y)) =20 /** * clamp_t - return a value clamped to a given range using a given type --=20 2.17.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales) From nobody Sat Feb 7 23:06:25 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 601D1C001DB for ; Fri, 4 Aug 2023 10:57:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230104AbjHDK5U convert rfc822-to-8bit (ORCPT ); Fri, 4 Aug 2023 06:57:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229582AbjHDK4y (ORCPT ); Fri, 4 Aug 2023 06:56:54 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7F134C0E for ; Fri, 4 Aug 2023 03:55:05 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-202-eiqKgpkyP26HhE95mGFrRA-1; Fri, 04 Aug 2023 11:55:03 +0100 X-MC-Unique: eiqKgpkyP26HhE95mGFrRA-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Fri, 4 Aug 2023 11:55:01 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Fri, 4 Aug 2023 11:55:01 +0100 From: David Laight To: "'linux-kernel@vger.kernel.org'" , "'Andy Shevchenko'" , 'Andrew Morton' , "'Matthew Wilcox (Oracle)'" , 'Christoph Hellwig' , "'Jason A. Donenfeld'" , 'Linus Torvalds' Subject: [PATCH v3 3/5] minmax: Fix indentation of __cmp_once() and __clamp_once() Thread-Topic: [PATCH v3 3/5] minmax: Fix indentation of __cmp_once() and __clamp_once() Thread-Index: AdnGwhrPydTNzZQYQuOxSX4R9e8zzQ== Date: Fri, 4 Aug 2023 10:55:01 +0000 Message-ID: <6dc20ac7cb6f4570a0160f076e8362e3@AcuMS.aculab.com> References: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> In-Reply-To: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Remove the extra indentation and align continuation markers. Signed-off-by: David Laight --- v3: No change v2: No change include/linux/minmax.h | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 6f79e44aad86..ccfbe003a643 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -33,11 +33,11 @@ #define __cmp(op, x, y) ((x) __cmp_op_##op (y) ? (x) : (y)) =20 #define __cmp_once(op, x, y, unique_x, unique_y) ({ \ - typeof(x) unique_x =3D (x); \ - typeof(y) unique_y =3D (y); \ - static_assert(__types_ok(x, y), \ - #op "(" #x ", " #y ") signedness error, fix types or consider " #op "_u= nsigned() before " #op "_t()"); \ - __cmp(op, unique_x, unique_y); }) + typeof(x) unique_x =3D (x); \ + typeof(y) unique_y =3D (y); \ + static_assert(__types_ok(x, y), \ + #op "(" #x ", " #y ") signedness error, fix types or consider " #op "_un= signed() before " #op "_t()"); \ + __cmp(op, unique_x, unique_y); }) =20 #define __careful_cmp(op, x, y) \ __builtin_choose_expr(__is_constexpr((x) - (y)), \ @@ -47,16 +47,16 @@ #define __clamp(val, lo, hi) \ ((val) >=3D (hi) ? (hi) : ((val) <=3D (lo) ? (lo) : (val))) =20 -#define __clamp_once(val, lo, hi, unique_val, unique_lo, unique_hi) ({ \ - typeof(val) unique_val =3D (val); \ - typeof(lo) unique_lo =3D (lo); \ - typeof(hi) unique_hi =3D (hi); \ - static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), \ - (lo) <=3D (hi), true), \ - "clamp() low limit " #lo " greater than high limit " #hi); \ - static_assert(__types_ok(val, lo), "clamp() 'lo' signedness error"); \ - static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error"); \ - __clamp(unique_val, unique_lo, unique_hi); }) +#define __clamp_once(val, lo, hi, unique_val, unique_lo, unique_hi) ({ \ + typeof(val) unique_val =3D (val); \ + typeof(lo) unique_lo =3D (lo); \ + typeof(hi) unique_hi =3D (hi); \ + static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), \ + (lo) <=3D (hi), true), \ + "clamp() low limit " #lo " greater than high limit " #hi); \ + static_assert(__types_ok(val, lo), "clamp() 'lo' signedness error"); \ + static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error"); \ + __clamp(unique_val, unique_lo, unique_hi); }) =20 #define __careful_clamp(val, lo, hi) ({ \ __builtin_choose_expr(__is_constexpr((val) - (lo) + (hi)), \ --=20 2.17.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales) From nobody Sat Feb 7 23:06:25 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77311C001DB for ; Fri, 4 Aug 2023 10:57:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231285AbjHDK5r convert rfc822-to-8bit (ORCPT ); Fri, 4 Aug 2023 06:57:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55246 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231735AbjHDK5P (ORCPT ); Fri, 4 Aug 2023 06:57:15 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5CF744EF6 for ; Fri, 4 Aug 2023 03:55:57 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-15--2foXNzwP2iEkhCH65UiWA-1; Fri, 04 Aug 2023 11:55:41 +0100 X-MC-Unique: -2foXNzwP2iEkhCH65UiWA-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Fri, 4 Aug 2023 11:55:39 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Fri, 4 Aug 2023 11:55:39 +0100 From: David Laight To: "'linux-kernel@vger.kernel.org'" , "'Andy Shevchenko'" , 'Andrew Morton' , "'Matthew Wilcox (Oracle)'" , 'Christoph Hellwig' , "'Jason A. Donenfeld'" , 'Linus Torvalds' Subject: [PATCH v3 4/5] minmax: Allow comparisons of 'int' against 'unsigned char/short'. Thread-Topic: [PATCH v3 4/5] minmax: Allow comparisons of 'int' against 'unsigned char/short'. Thread-Index: AdnGwjJw1R+iwy+yQTyatTq077Viag== Date: Fri, 4 Aug 2023 10:55:39 +0000 Message-ID: <423c552b375c46ddab16488d33dee528@AcuMS.aculab.com> References: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> In-Reply-To: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Since 'unsigned char/short' get promoted to 'signed int' it is safe to compare them against an 'int' value. Signed-off-by: David Laight --- v3; No change v2: No change include/linux/minmax.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index ccfbe003a643..f56611ab486a 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -24,8 +24,9 @@ __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \ is_signed_type(typeof(x)), 0) =20 -#define __types_ok(x, y) \ - (__is_signed(x) =3D=3D __is_signed(y)) +#define __types_ok(x, y) \ + (__is_signed(x) =3D=3D __is_signed(y) || \ + __is_signed((x) + 0) =3D=3D __is_signed((y) + 0)) =20 #define __cmp_op_min < #define __cmp_op_max > --=20 2.17.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales) From nobody Sat Feb 7 23:06:25 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46A20C001DB for ; Fri, 4 Aug 2023 10:58:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230423AbjHDK6p convert rfc822-to-8bit (ORCPT ); Fri, 4 Aug 2023 06:58:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231654AbjHDK5f (ORCPT ); Fri, 4 Aug 2023 06:57:35 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 712AA524D for ; Fri, 4 Aug 2023 03:56:45 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mtapsc-5-bkO1WbUpNhKPKRaGR9bvIg-1; Fri, 04 Aug 2023 11:56:23 +0100 X-MC-Unique: bkO1WbUpNhKPKRaGR9bvIg-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Fri, 4 Aug 2023 11:56:21 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Fri, 4 Aug 2023 11:56:21 +0100 From: David Laight To: "'linux-kernel@vger.kernel.org'" , "'Andy Shevchenko'" , 'Andrew Morton' , "'Matthew Wilcox (Oracle)'" , 'Christoph Hellwig' , "'Jason A. Donenfeld'" , 'Linus Torvalds' Subject: [PATCH v3 5/5] minmax: Relax check to allow comparison between int and small unsigned constants. Thread-Topic: [PATCH v3 5/5] minmax: Relax check to allow comparison between int and small unsigned constants. Thread-Index: AdnGwkt6hGqNS4p3Ts2CQBK2yLMoFA== Date: Fri, 4 Aug 2023 10:56:21 +0000 Message-ID: References: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> In-Reply-To: <01e3e09005e9434b8f558a893a47c053@AcuMS.aculab.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Convert constants between 0 and INT_MAX to 'int' prior to comparisons so that min(signed_var, 20u) and, more commonly, min(signed_var, sizeof()) are both valid. Signed-off-by: David Laight --- v3: Fix compiler warnings for 'x >=3D 0' with unsigned/pointer types. v2: Add cast to fix min/max with pointer types. include/linux/minmax.h | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index f56611ab486a..8d292aa55f5f 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -8,11 +8,13 @@ /* * min()/max()/clamp() macros must accomplish three things: * - * - avoid multiple evaluations of the arguments (so side-effects like + * - Avoid multiple evaluations of the arguments (so side-effects like * "x++" happen only once) when non-constant. - * - perform signed v unsigned type-checking (to generate compile + * - Perform signed v unsigned type-checking (to generate compile * errors instead of nasty runtime surprises). - * - retain result as a constant expressions when called with only + * Constants from 0 to INT_MAX are cast to (int) so can be used + * in comparisons with signed types. + * - Retain result as a constant expressions when called with only * constant expressions (to avoid tripping VLA warnings in stack * allocation usage). */ @@ -24,9 +26,17 @@ __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \ is_signed_type(typeof(x)), 0) =20 -#define __types_ok(x, y) \ - (__is_signed(x) =3D=3D __is_signed(y) || \ - __is_signed((x) + 0) =3D=3D __is_signed((y) + 0)) +#define __is_noneg_int(x) \ + (__builtin_choose_expr(!__is_constexpr(x), false, \ + __builtin_choose_expr(__is_signed(x), x, 0) >=3D 0 && \ + (x) <=3D (typeof((x) + 0))(long)__INT_MAX__)) + +#define __int_const(x) __builtin_choose_expr(__is_noneg_int(x), (int)(long= )(x), (x)) + +#define __types_ok(x, y) \ + (__is_signed(x) =3D=3D __is_signed(y) || \ + __is_signed((x) + 0) =3D=3D __is_signed((y) + 0) || \ + __is_noneg_int(x) || __is_noneg_int(y)) =20 #define __cmp_op_min < #define __cmp_op_max > @@ -34,24 +44,24 @@ #define __cmp(op, x, y) ((x) __cmp_op_##op (y) ? (x) : (y)) =20 #define __cmp_once(op, x, y, unique_x, unique_y) ({ \ - typeof(x) unique_x =3D (x); \ - typeof(y) unique_y =3D (y); \ + typeof(__int_const(x)) unique_x =3D (x); \ + typeof(__int_const(y)) unique_y =3D (y); \ static_assert(__types_ok(x, y), \ #op "(" #x ", " #y ") signedness error, fix types or consider " #op "_un= signed() before " #op "_t()"); \ __cmp(op, unique_x, unique_y); }) =20 #define __careful_cmp(op, x, y) \ __builtin_choose_expr(__is_constexpr((x) - (y)), \ - __cmp(op, x, y), \ + __cmp(op, __int_const(x), __int_const(y)), \ __cmp_once(op, x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y))) =20 #define __clamp(val, lo, hi) \ ((val) >=3D (hi) ? (hi) : ((val) <=3D (lo) ? (lo) : (val))) =20 #define __clamp_once(val, lo, hi, unique_val, unique_lo, unique_hi) ({ \ - typeof(val) unique_val =3D (val); \ - typeof(lo) unique_lo =3D (lo); \ - typeof(hi) unique_hi =3D (hi); \ + typeof(__int_const(val)) unique_val =3D (val); \ + typeof(__int_const(lo)) unique_lo =3D (lo); \ + typeof(__int_const(hi)) unique_hi =3D (hi); \ static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), \ (lo) <=3D (hi), true), \ "clamp() low limit " #lo " greater than high limit " #hi); \ --=20 2.17.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales)