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=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 27407C433B4 for ; Mon, 10 May 2021 07:09:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EDC53611F1 for ; Mon, 10 May 2021 07:09:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230111AbhEJHKP (ORCPT ); Mon, 10 May 2021 03:10:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49706 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230002AbhEJHKO (ORCPT ); Mon, 10 May 2021 03:10:14 -0400 Received: from mail-wr1-x42f.google.com (mail-wr1-x42f.google.com [IPv6:2a00:1450:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 956F8C061573 for ; Mon, 10 May 2021 00:09:10 -0700 (PDT) Received: by mail-wr1-x42f.google.com with SMTP id z6so15404692wrm.4 for ; Mon, 10 May 2021 00:09:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:references:from:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=GviCxizU8MAUq4BsmVs+vwODzzoFDedx2IBplXZauj8=; b=M1dx8zr/gHnHQOlhsZKbOn9pC3BP5EHGiY9bp2yqwjdhLXlThan2OqesRnPMFRzQzc FxDnP4HWljQ7GDtAaOm47NflUAT7CaNaChoCsdy/cRtfiZuM6PxgA51VmaQSSa98DGbn Yxiuc89vDHab3Bc508aRM0ETESFutlbyct5FxeahhBigBBl8dv2WJLBn9+Y+B0XECSza XoGWwzjFmqvrbmv3RZSuIiEsh8PowcgaiNGyCed308pD7vSBtorDpP5lH0+oxEuXkdAS sXAt6rEzs5IxZH0O0hvsciIl7rZ6yazVdYhaaM9CKTzNUNDunQ9f7/Sno11wCpOs7C87 /FFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=GviCxizU8MAUq4BsmVs+vwODzzoFDedx2IBplXZauj8=; b=qvET4lAq7KQHR8njLtY1RtOLOP0bksmVnh8YmQLMqw0KIWRwXqFex1u/8WafkzROoY 1l7HK1xJZF34ox5z/GqFgATQISeGkd69CZc52ZsC6USjhqzShlbpI5IBaX+E0d7HdHof AFjriCW2m2ePytbK3DxRKGmg/vBMKK4uRK5osz6aKQoUV3EbJ0ep2EhpwKgTz+OHxgaH RbgX6XDxgFBkNaolrcZcXbYEEziw48qTOlDYevta5Yzhp2zJyKdZx7mOG/La7nJ0eq5E 4XwoXSJ2jMxigP1p6+m7SDXQmvvOfpTQFSuovYrdp0sWW28QmHRlWYsSnpeZHmtrWSpN O3Eg== X-Gm-Message-State: AOAM53159EIG4vL6fKGfoyQWEKD1u6T2FExxFnaJqfz/LZ7Qcct4HJPO TAfilsDQ2gPWDpYvAp8IF3U= X-Google-Smtp-Source: ABdhPJywCcT+i2PYTAikddPCzFdrhEdSc43GQBrxr7GDcoWsvQ5Y3PUWGvZ6RqOr5KPBAZSnQOwvpQ== X-Received: by 2002:adf:efca:: with SMTP id i10mr28999537wrp.284.1620630549410; Mon, 10 May 2021 00:09:09 -0700 (PDT) Received: from ?IPv6:2003:ea:8f38:4600:7d85:535b:ab9d:c06e? (p200300ea8f3846007d85535bab9dc06e.dip0.t-ipconnect.de. [2003:ea:8f38:4600:7d85:535b:ab9d:c06e]) by smtp.googlemail.com with ESMTPSA id n2sm21717904wmb.32.2021.05.10.00.09.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 May 2021 00:09:09 -0700 (PDT) To: Christoph Hellwig Cc: Bjorn Helgaas , "linux-pci@vger.kernel.org" , Bjorn Helgaas References: <5719b91c-9f91-0029-0a28-386f1cb29d31@gmail.com> From: Heiner Kallweit Subject: Re: [PATCH v2] PCI/VPD: Use unaligned access helpers in pci_vpd_read Message-ID: <26a9b3ec-07dc-c474-25ad-d7082060d305@gmail.com> Date: Mon, 10 May 2021 09:09:02 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 10.05.2021 08:36, Christoph Hellwig wrote: > On Sat, May 08, 2021 at 12:29:15AM +0200, Heiner Kallweit wrote: >> + >> + if (len == 4) { >> + put_unaligned_le32(val, buf); >> + } else { >> + cpu_to_le32s(&val); >> + memcpy(buf, (u8 *)&val + skip, len); > > cpu_to_le32s is a horrible API that breaks endianess annotations. > The endian-adjusted value is used just in the next line, so I think there's no risk of wrong usage. But yes, this function converts to le32 w/o using __bitwise. Therefore I understand the concern. > Is the intent of this code to only put 16 bits in? Why not something > like: > > switch (len) { > case 4: > put_unaligned_le32(val, buf); > break; > case 2: > put_unaligned_le16(val, buf + 2); > break; > case 1: > buf[3] = val; > break; > } > len can have any value 1 .. 4. Also the proposal doesn't consider the skip value.