From nobody Thu Oct 2 06:14:53 2025 Received: from fra-out-008.esa.eu-central-1.outbound.mail-perimeter.amazon.com (fra-out-008.esa.eu-central-1.outbound.mail-perimeter.amazon.com [35.158.23.94]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AAF8A2FF658; Mon, 22 Sep 2025 10:31:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=35.158.23.94 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758537117; cv=none; b=UQF83PtUIhVfCP0lOKpTDjpQE7ad+6hJzNp6ifGaJ5XhmY7xohx9PxzgRcU23Nd5RhKM2/nSL6oIGHMYTCNJJAmlzzQYwYNX9mRxbCL2sZLCV2uTqiq5ynWvBDj92a7wDWlwdtnUQtHamU3H+dzFiYsDELWzJw2qCUHj4IeVjAc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758537117; c=relaxed/simple; bh=7o6n/7afD73I8KmTywLVAVDBtvL4BDHX8Eeq0ODATQ8=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Iam1j86lBPuIVnm0/FvvOZKfPME4OzYBGjWQK+oBLKSOyDke4LIVa+T9D1vpJ6ICH8SsoW0LPqpZq4EJukXdxJjqwBq/d7dIHOfxOrvHlzE9KDKc42mHOd8/kfpOQc7O230iRWKdv1c62LubheaHoeLQD38ij7ASkvLixnTxjXs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b=ZseQaM3n; arc=none smtp.client-ip=35.158.23.94 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b="ZseQaM3n" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1758537113; x=1790073113; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=0AzpApDbX8CFEbC2P7WHNPH2gra+XDIh1eSQ6GUhJZw=; b=ZseQaM3nTjv3PEFbsnEiEgbYj455X727P54JTylRyNc5ukaNrKduwNKG ZWmVV2GPyjEL04BvCeXVvUdwQJo5HP1NVzdG2AjW5j12TIOGU6XGrJgDt taXloW3cDOsw5cdK2Wo0rRdxTA8HwRBKOpvnj4pucpbvHvsrtoJZLgCca 2yOE442T7Pveha12L+FRNDvgbeN9/cwy5ZeWKNLTm4ImkSx/Fva7DZubk 81mx4EadXOG4CP9xJWBcbArXdMmOdPeRDiXRY+00+rlJcBiXhMlgRo9Er c33WUlhlVwWvLJkTmfqSLgUmNjteVesTKpPk9P4eF52zHwV34hQ8qQes1 Q==; X-CSE-ConnectionGUID: odvq3ZZpTyS49u8i0Iy5eQ== X-CSE-MsgGUID: SOYQmnpzS2mAx3i733nmYA== X-IronPort-AV: E=Sophos;i="6.18,284,1751241600"; d="scan'208";a="2478545" Received: from ip-10-6-3-216.eu-central-1.compute.internal (HELO smtpout.naws.eu-central-1.prod.farcaster.email.amazon.dev) ([10.6.3.216]) by internal-fra-out-008.esa.eu-central-1.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Sep 2025 10:31:42 +0000 Received: from EX19MTAEUB001.ant.amazon.com [54.240.197.234:13846] by smtpin.naws.eu-central-1.prod.farcaster.email.amazon.dev [10.0.23.64:2525] with esmtp (Farcaster) id b99996d2-d45b-4a9d-96e4-d87059b0f7bf; Mon, 22 Sep 2025 10:31:42 +0000 (UTC) X-Farcaster-Flow-ID: b99996d2-d45b-4a9d-96e4-d87059b0f7bf Received: from EX19D018EUA004.ant.amazon.com (10.252.50.85) by EX19MTAEUB001.ant.amazon.com (10.252.51.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Mon, 22 Sep 2025 10:31:42 +0000 Received: from dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com (172.19.116.181) by EX19D018EUA004.ant.amazon.com (10.252.50.85) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Mon, 22 Sep 2025 10:31:37 +0000 From: Eliav Farber To: , , , , , CC: Andy Shevchenko , Christoph Hellwig , Dan Carpenter , "Jason A. Donenfeld" , Jens Axboe , Lorenzo Stoakes , Mateusz Guzik , "Matthew Wilcox" , Pedro Falcato Subject: [PATCH 2/7 6.12.y] minmax.h: update some comments Date: Mon, 22 Sep 2025 10:31:18 +0000 Message-ID: <20250922103123.14538-3-farbere@amazon.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250922103123.14538-1-farbere@amazon.com> References: <20250922103123.14538-1-farbere@amazon.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: EX19D039UWB003.ant.amazon.com (10.13.138.93) To EX19D018EUA004.ant.amazon.com (10.252.50.85) Content-Type: text/plain; charset="utf-8" From: David Laight [ Upstream commit 10666e99204818ef45c702469488353b5bb09ec7 ] - Change three to several. - Remove the comment about retaining constant expressions, no longer true. - Realign to nearer 80 columns and break on major punctiation. - Add a leading comment to the block before __signed_type() and __is_nonneg= () Otherwise the block explaining the cast is a bit 'floating'. Reword the rest of that comment to improve readability. Link: https://lkml.kernel.org/r/85b050c81c1d4076aeb91a6cded45fee@AcuMS.acul= ab.com Signed-off-by: David Laight Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton Signed-off-by: Eliav Farber --- include/linux/minmax.h | 53 +++++++++++++++++++----------------------- 1 file changed, 24 insertions(+), 29 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 51b0d988e322..24e4b372649a 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -8,13 +8,10 @@ #include =20 /* - * min()/max()/clamp() macros must accomplish three things: + * min()/max()/clamp() macros must accomplish several things: * * - Avoid multiple evaluations of the arguments (so side-effects like * "x++" happen only once) when non-constant. - * - Retain result as a constant expressions when called with only - * constant expressions (to avoid tripping VLA warnings in stack - * allocation usage). * - Perform signed v unsigned type-checking (to generate compile * errors instead of nasty runtime surprises). * - Unsigned char/short are always promoted to signed int and can be @@ -31,25 +28,23 @@ * bit #0 set if ok for unsigned comparisons * bit #1 set if ok for signed comparisons * - * In particular, statically non-negative signed integer - * expressions are ok for both. + * In particular, statically non-negative signed integer expressions + * are ok for both. * - * NOTE! Unsigned types smaller than 'int' are implicitly - * converted to 'int' in expressions, and are accepted for - * signed conversions for now. This is debatable. + * NOTE! Unsigned types smaller than 'int' are implicitly converted to 'in= t' + * in expressions, and are accepted for signed conversions for now. + * This is debatable. * - * Note that 'x' is the original expression, and 'ux' is - * the unique variable that contains the value. + * Note that 'x' is the original expression, and 'ux' is the unique variab= le + * that contains the value. * - * We use 'ux' for pure type checking, and 'x' for when - * we need to look at the value (but without evaluating - * it for side effects! Careful to only ever evaluate it - * with sizeof() or __builtin_constant_p() etc). + * We use 'ux' for pure type checking, and 'x' for when we need to look at= the + * value (but without evaluating it for side effects! + * Careful to only ever evaluate it with sizeof() or __builtin_constant_p(= ) etc). * - * Pointers end up being checked by the normal C type - * rules at the actual comparison, and these expressions - * only need to be careful to not cause warnings for - * pointer use. + * Pointers end up being checked by the normal C type rules at the actual + * comparison, and these expressions only need to be careful to not cause + * warnings for pointer use. */ #define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux)) #define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4)) @@ -57,19 +52,19 @@ __signed_type_use(x, ux) : __unsigned_type_use(x, ux)) =20 /* - * To avoid warnings about casting pointers to integers - * of different sizes, we need that special sign type. + * Check whether a signed value is always non-negative. * - * On 64-bit we can just always use 'long', since any - * integer or pointer type can just be cast to that. + * A cast is needed to avoid any warnings from values that aren't signed + * integer types (in which case the result doesn't matter). * - * This does not work for 128-bit signed integers since - * the cast would truncate them, but we do not use s128 - * types in the kernel (we do use 'u128', but they will - * be handled by the !is_signed_type() case). + * On 64-bit any integer or pointer type can safely be cast to 'long'. + * But on 32-bit we need to avoid warnings about casting pointers to integ= ers + * of different sizes without truncating 64-bit values so 'long' or 'long = long' + * must be used depending on the size of the value. * - * NOTE! The cast is there only to avoid any warnings - * from when values that aren't signed integer types. + * This does not work for 128-bit signed integers since the cast would tru= ncate + * them, but we do not use s128 types in the kernel (we do use 'u128', + * but they are handled by the !is_signed_type() case). */ #ifdef CONFIG_64BIT #define __signed_type(ux) long --=20 2.47.3