Received: by 2002:a05:6a10:9e8c:0:0:0:0 with SMTP id y12csp609799pxx;
        Thu, 29 Oct 2020 10:04:19 -0700 (PDT)
X-Google-Smtp-Source: ABdhPJweu5zLbNIWJHcBEz8RAy7cEoeKlo68aSMmMcloPu7fynEI90Pn/A8gBchrj5QZ8WLsaltQ
X-Received: by 2002:a17:906:6702:: with SMTP id a2mr4880041ejp.309.1603991059527;
        Thu, 29 Oct 2020 10:04:19 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1603991059; cv=none;
        d=google.com; s=arc-20160816;
        b=GVaZF6HSvsiP5zbWVbZKNxLbzvSeSJanXPv0PtoeHw743r39xN+RicGv2feCZ/dvnv
         +waCiwr0DvE8IYG1TSsCAPa4l19tMD7KmIF3glZzsW0Zlkn2H+1RH4hmdn/09qsm7R3I
         Whf2ugrLWndYC4lh5Db4f1EHLLqSqFHo2PkF5EVzv8eqF1FIFxaCuWwyf7Dqz+/q/AIN
         UNacMxNB/Om4qxxbGuc9RMHeyQs/gxaEOcXg8zsFD1f9cRIZ5lr08zakHV9k6ip81shA
         5UpddZVpcKOhNVtZ/xY0i2OWwDfYxeBAfQ5AD528T4aKoW/wVSUfXwmXJ/8PyjD3967U
         eoRQ==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
        h=list-id:precedence:content-transfer-encoding:content-language
         :in-reply-to:mime-version:user-agent:date:message-id:from:references
         :cc:to:subject:dkim-signature;
        bh=LFIk1KDbaI+imFseS7EgKO+PMROEHyYFYHvDyMX5vJs=;
        b=kbN4szcV03Ltk5+TTTSI90uVA+zxwFyaI0nzO4NzGnS1gBybPIQxSpdcSmMJ11fhyz
         txHOKJO4vpozOvvKKITOsvJIzp7ndz2ANAYLnGjqpbWjUrkc4sB8z/9fxYAnHxpAepbF
         TLTyb4V/okWpbbD1aYojOB453bnSLR8TecJfxXHP0670aku//MRCgbfRHTyJIReD55Xl
         +tn6KLT14+rQ0MO+95FaYFLi5Kr4ZDwIrPTy2w5fEgT9Ps5EAVGc4GLPcBmmyK82a1iT
         MS9RyTKsAbYSlC0PBbQjsvL811w3wi4cwX6ML8FbryuoU6Ol8tkYmF18+Ws7VBshANB5
         iTGw==
ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=hjOoUMdE;
       spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org;
       dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18])
        by mx.google.com with ESMTP id a12si1551517edy.403.2020.10.29.10.03.55;
        Thu, 29 Oct 2020 10:04:19 -0700 (PDT)
Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=hjOoUMdE;
       spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org;
       dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1726050AbgJ2RAD (ORCPT <rfc822;ivid.suvarna@gmail.com>
        + 99 others); Thu, 29 Oct 2020 13:00:03 -0400
Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39117 "EHLO
        us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK)
        by vger.kernel.org with ESMTP id S1726333AbgJ2RAD (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 29 Oct 2020 13:00:03 -0400
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;
        s=mimecast20190719; t=1603990801;
        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=LFIk1KDbaI+imFseS7EgKO+PMROEHyYFYHvDyMX5vJs=;
        b=hjOoUMdEhKbC/FwAehxMJQHpabeSX0YJG9PS85qz3m3cgjcbUZ9mNmRMu4BVkgmWLDKH4m
        ZaHcvPhA8aotq+XkgNQ3JYfx29LJM4W4MMJmydoFajqkCnTh59wTPP8TczMGYF5GU87XH+
        uqEj82fX0KgqWJ5tDgD3EsgBlLtOVLk=
Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com
 [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id
 us-mta-357-FEaI1KGUPWO2-iDtL-5X5w-1; Thu, 29 Oct 2020 12:59:58 -0400
X-MC-Unique: FEaI1KGUPWO2-iDtL-5X5w-1
Received: by mail-wr1-f70.google.com with SMTP id h8so1530829wrt.9
        for <linux-kernel@vger.kernel.org>; Thu, 29 Oct 2020 09:59:58 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20161025;
        h=x-gm-message-state:subject:to:cc:references:from:message-id:date
         :user-agent:mime-version:in-reply-to:content-language
         :content-transfer-encoding;
        bh=LFIk1KDbaI+imFseS7EgKO+PMROEHyYFYHvDyMX5vJs=;
        b=q3DC8j09Eid+103/aysdSR8N9LiEZlWb/z0Ii7lfsHt4svro9pCn2AyXg1Pzi51Ckx
         NxYVuhJOCuAVrQdkbm1AkOf/SbPDFEKxkcbFxZUnrCqpWx5JbcnwK3ek1RfeaIEspM2T
         7CFZfcb7to4NPrER09/F+doIJN6mC37mxX6KgpOGmqevE8/xdLuzLaM0UawvixkHNXE8
         vLjZhnGDsDzQWbkDSQS6D9MryavdzTdZdYWciWKrLAp3uG1Ci3RqjjGjo0CV/rQpp9jw
         Yad/sXLfrMbyfyAoALb3bruGTWGk5px+xNnbZTcGs4nm3LABBBTtm6Ici5duqQ07iXrT
         SPOg==
X-Gm-Message-State: AOAM531FzNIHZb6IKk3a1+2M6xy2nKSJKNSgjPLaMattIGctBoNsIqW2
        UF6lBa43uuHebXx+j03ZbSGXtDKqjGKdjU+1ygq+RybZ2Zirrci52HqIJ6885NJU56kDPMi9xbi
        3cMaZ9Ke+S1HW1ikBsrKj5Vnj
X-Received: by 2002:a5d:4e8d:: with SMTP id e13mr6897921wru.368.1603990797492;
        Thu, 29 Oct 2020 09:59:57 -0700 (PDT)
X-Received: by 2002:a5d:4e8d:: with SMTP id e13mr6897898wru.368.1603990797308;
        Thu, 29 Oct 2020 09:59:57 -0700 (PDT)
Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a])
        by smtp.gmail.com with ESMTPSA id f17sm6577560wrm.27.2020.10.29.09.59.55
        (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128);
        Thu, 29 Oct 2020 09:59:56 -0700 (PDT)
Subject: Re: [PATCH] [v2] x86: apic: avoid -Wshadow warning in header
To:     Arvind Sankar <nivedita@alum.mit.edu>,
        David Laight <David.Laight@ACULAB.COM>
Cc:     'Arnd Bergmann' <arnd@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "x86@kernel.org" <x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "platform-driver-x86@vger.kernel.org" 
        <platform-driver-x86@vger.kernel.org>,
        "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>
References: <20201028212417.3715575-1-arnd@kernel.org>
 <38b11ed3fec64ebd82d6a92834a4bebe@AcuMS.aculab.com>
 <20201029165611.GA2557691@rani.riverdale.lan>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <93180c2d-268c-3c33-7c54-4221dfe0d7ad@redhat.com>
Date:   Thu, 29 Oct 2020 17:59:54 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.3.1
MIME-Version: 1.0
In-Reply-To: <20201029165611.GA2557691@rani.riverdale.lan>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 29/10/20 17:56, Arvind Sankar wrote:
>> For those two just add:
>> 	struct apic *apic = x86_system_apic;
>> before all the assignments.
>> Less churn and much better code.
>>
> Why would it be better code?
> 

I think he means the compiler produces better code, because it won't
read the global variable repeatedly.  Not sure if that's true,(*) but I
think I do prefer that version if Arnd wants to do that tweak.

Paolo

(*) if it is, it might also be due to Linux using -fno-strict-aliasing