From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A7EBC432C0 for ; Wed, 27 Nov 2019 18:06:31 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0BFE820874 for ; Wed, 27 Nov 2019 18:06:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BFE820874 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id D6E43221CC; Wed, 27 Nov 2019 18:06:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Hs3Pb6KK78g5; Wed, 27 Nov 2019 18:06:29 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 099CD2076F; Wed, 27 Nov 2019 18:06:29 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 016EDC1DD5; Wed, 27 Nov 2019 18:06:29 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id E1FEEC0881 for ; Wed, 27 Nov 2019 18:06:26 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id D05A62154E for ; Wed, 27 Nov 2019 18:06:26 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id tKPjhgMdPVKr for ; Wed, 27 Nov 2019 18:06:25 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by silver.osuosl.org (Postfix) with ESMTP id D1DD42076F for ; Wed, 27 Nov 2019 18:06:25 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1924431B; Wed, 27 Nov 2019 10:06:25 -0800 (PST) Received: from [10.1.196.37] (e121345-lin.cambridge.arm.com [10.1.196.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 210853F6C4; Wed, 27 Nov 2019 10:06:20 -0800 (PST) Subject: Re: [PATCH v3 1/7] linux/log2.h: Add roundup/rounddown_pow_two64() family of functions To: Leon Romanovsky , Nicolas Saenz Julienne References: <20191126091946.7970-1-nsaenzjulienne@suse.de> <20191126091946.7970-2-nsaenzjulienne@suse.de> <20191126125137.GA10331@unreal> From: Robin Murphy Message-ID: <6e0b9079-9efd-2884-26d1-3db2d622079d@arm.com> Date: Wed, 27 Nov 2019 18:06:18 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191126125137.GA10331@unreal> Content-Language: en-GB Cc: Heiko Stuebner , linux-pci@vger.kernel.org, Shawn Lin , Hanjun Guo , Frank Rowand , Christoph Hellwig , f.fainelli@gmail.com, linux-rockchip@lists.infradead.org, linux-rdma@vger.kernel.org, maz@kernel.org, phil@raspberrypi.org, linux-acpi@vger.kernel.org, Len Brown , devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, Bjorn Helgaas , linux-arm-kernel@lists.infradead.org, mbrugger@suse.com, netdev@vger.kernel.org, "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, jeremy.linton@arm.com, iommu@lists.linux-foundation.org, Rob Herring , wahrenst@gmx.net, james.quinlan@broadcom.com, Sudeep Holla , "David S. Miller" , Tariq Toukan X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 26/11/2019 12:51 pm, Leon Romanovsky wrote: > On Tue, Nov 26, 2019 at 10:19:39AM +0100, Nicolas Saenz Julienne wrote: >> Some users need to make sure their rounding function accepts and returns >> 64bit long variables regardless of the architecture. Sadly >> roundup/rounddown_pow_two() takes and returns unsigned longs. Create a >> new generic 64bit variant of the function and cleanup rougue custom >> implementations. > > Is it possible to create general roundup/rounddown_pow_two() which will > work correctly for any type of variables, instead of creating special > variant for every type? In fact, that is sort of the case already - roundup_pow_of_two() itself wraps ilog2() such that the constant case *is* type-independent. And since ilog2() handles non-constant values anyway, might it be reasonable to just take the strongly-typed __roundup_pow_of_two() helper out of the loop as below? Robin ----->8----- diff --git a/include/linux/log2.h b/include/linux/log2.h index 83a4a3ca3e8a..e825f8a6e8b5 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -172,11 +172,8 @@ unsigned long __rounddown_pow_of_two(unsigned long n) */ #define roundup_pow_of_two(n) \ ( \ - __builtin_constant_p(n) ? ( \ - (n == 1) ? 1 : \ - (1UL << (ilog2((n) - 1) + 1)) \ - ) : \ - __roundup_pow_of_two(n) \ + (__builtin_constant_p(n) && (n == 1)) ? \ + 1 : (1UL << (ilog2((n) - 1) + 1)) \ ) /** _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu