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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3423C54E94 for ; Thu, 26 Jan 2023 10:42:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237005AbjAZKmd (ORCPT ); Thu, 26 Jan 2023 05:42:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231428AbjAZKmc (ORCPT ); Thu, 26 Jan 2023 05:42:32 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3286367D3 for ; Thu, 26 Jan 2023 02:41:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674729706; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nSKGSRAw4zApLqZOZxojx5gSJ8OH2ShG8cSG815Lldg=; b=B0EFAhwNbslbtxP7GyCLaYg1bTbvfQOvQ66MIxaMljxr/5BJXsz4GziPVGMHBPl8fqx3jX auhhnUFnwm30TCU58XoM1Y5hFRYY8QUMgb84RZc3jAZnEXOLiMhCFhhRG294m296uxjy73 xMdmc/FF28DJ7f/ERFY2WUuxPx2+bhY= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-20-tLObk3vXM7uga8b56aLINA-1; Thu, 26 Jan 2023 05:41:43 -0500 X-MC-Unique: tLObk3vXM7uga8b56aLINA-1 Received: by mail-wm1-f72.google.com with SMTP id l5-20020a1ced05000000b003db300f2e1cso334667wmh.0 for ; Thu, 26 Jan 2023 02:41:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:subject:organization:from :references:cc:to:content-language:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=nSKGSRAw4zApLqZOZxojx5gSJ8OH2ShG8cSG815Lldg=; b=S6hBhtkaqwu1kQSytZp2DkOaDSo2YOYa7l1Ok0hdkvVO+/kmS13oKfEFDfm7vhL4ZT K4kTQy4BHmYPYU+l/FPMiBxaxZS91ElZkJ6t42C3qsh7tZwSbQfkmigBZ5wr7zwNDc8p Bg/E+YFimUtZxdIgSU/KHE84fCm+z/onSme2nU/WDx6C9ZGfffvAyrl7lZJrcZVK4FXE Lm1S5sG8BoWpy1vQmxhRQUaL9xLB71OKRmE8iwHycmexBZQnYpfTUPXj86O+6b4JO60W +Ero3PQs5DNgUBB57/1THT3ePdu81uMTFV307R6uiqM/LbJ2CsHlXQB71ZJcAfS+xUAD Dihg== X-Gm-Message-State: AFqh2kpQ9Xh9okNGxAXIejNcKtfK/t3T3n4LjkTtfHBVV0VmZW73Tmox ke3/wwFJe4ZXKVaBXbCll6NLh9NqS111seKYmQMtrtE7OZY1qAsp/DB8PhYNcBUVtY/xtQ2ZK5S IplDgSpmzECOLQJwRE3o1iyv/ X-Received: by 2002:a05:600c:1695:b0:3d3:4ae6:a71b with SMTP id k21-20020a05600c169500b003d34ae6a71bmr33303918wmn.2.1674729702027; Thu, 26 Jan 2023 02:41:42 -0800 (PST) X-Google-Smtp-Source: AMrXdXvWhy4TGOvCPFAbQoLxK9D8awwiSNTdJq0Nz5MUw3B7wix4cF4N7mvyXVyul/6m5yzASpKTpA== X-Received: by 2002:a05:600c:1695:b0:3d3:4ae6:a71b with SMTP id k21-20020a05600c169500b003d34ae6a71bmr33303893wmn.2.1674729701735; Thu, 26 Jan 2023 02:41:41 -0800 (PST) Received: from ?IPV6:2a09:80c0:192:0:5dac:bf3d:c41:c3e7? ([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id u11-20020a05600c19cb00b003d9fb04f658sm4683254wmq.4.2023.01.26.02.41.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 Jan 2023 02:41:41 -0800 (PST) Message-ID: Date: Thu, 26 Jan 2023 11:41:40 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Content-Language: en-US To: David Howells Cc: Al Viro , Christoph Hellwig , Matthew Wilcox , Jens Axboe , Jan Kara , Jeff Layton , Jason Gunthorpe , Logan Gunthorpe , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , John Hubbard References: <20230125210657.2335748-1-dhowells@redhat.com> <20230125210657.2335748-2-dhowells@redhat.com> <2613249.1674726566@warthog.procyon.org.uk> <2638928.1674729230@warthog.procyon.org.uk> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] iov_iter: Use __bitwise with the extraction_flags In-Reply-To: <2638928.1674729230@warthog.procyon.org.uk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26.01.23 11:33, David Howells wrote: > Interestingly, things like __be32 are __bitwise. I wonder if that actually > makes sense or if it was just convenient so stop people doing arithmetic on > them. I guess doing AND/OR/XOR on them isn't a problem provided both > arguments are appropriately byte-swapped. I recall that __be32 and friends were one of the early users of __bitwise in the kernel. And the reason IIRC was exactly that: detect when no proper conversion was performed using static code analysis (Sparse). While some operations might make sense, the abuse is much more likely. LGTM, thanks! -- Thanks, David / dhildenb