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=-3.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 97493C43464 for ; Fri, 18 Sep 2020 20:29:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3814823119 for ; Fri, 18 Sep 2020 20:29:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HOwkJz9c" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726305AbgIRU3N (ORCPT ); Fri, 18 Sep 2020 16:29:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726200AbgIRU3M (ORCPT ); Fri, 18 Sep 2020 16:29:12 -0400 Received: from mail-qt1-x842.google.com (mail-qt1-x842.google.com [IPv6:2607:f8b0:4864:20::842]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FA03C0613CE for ; Fri, 18 Sep 2020 13:29:12 -0700 (PDT) Received: by mail-qt1-x842.google.com with SMTP id v54so6230377qtj.7 for ; Fri, 18 Sep 2020 13:29:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=zA0vgj4MEhN7seo0nt8TRqqpQ53wlISAhciKlAtPvC4=; b=HOwkJz9c3WOAfVav8KySepB69cP4Tpb1FVnfRTQdmWHQn0jpmEpAIasccrNxf0WM+s CvbNcuoS1TVSlJ1b7OecnaiI4QYtqHc+db2lbrnWdafYCT+PpmbuKXgEWGi738avmBu0 4j1O4cC5pfUD85v9O/dB48vWBZrovSrMJv+igfK6EtCT51ck0XysxKFQrm8LMUr7c6R8 GTFKupqVbDNxWq32L3OypEM3XYw8tsTZ0OgQqmF9tbZcsoGPMIzT8JaxozzK97gzvSSB oaaas32cILbzEjCuvrWgl7tYsaN/+iSbD4KOvcPA1dvc4fz03hx4XH+HGCh358ZvqARi vT0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:date:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=zA0vgj4MEhN7seo0nt8TRqqpQ53wlISAhciKlAtPvC4=; b=XBerzidYc/2cibHvZcRdDt0aZQEJFtqxDOsiwH6CRqKiLnvBGwbwYJz6IZ180RxlGz YRv0kDQ5Oq3NQgeHC7E/osNQHTToyXfZknJy/aLn63B+FA7GXXJ/XiQAfP/E5SOdK4AC GWmQXe25JHyBNgS+TV+T/47lttRAtH1CLNxLGYP5ibS0I+/n45g5dy/l5AtCl9c6lZwx cBMte/wPQdUMgoOhWThxrxXEG4bEyjBNkTzz8JBBAGTR2jqfhiNefFkIFZYylMkLf0tZ Kkr17IQ8aUZhNE1bi2KIwqlyyiEsktwULlKok/TeM4Ixd9HTcYWWiCJCAW5uC+jeWh0F cQ6A== X-Gm-Message-State: AOAM533B0rgS6tv8jCW5JNkHOlsb/o7Lc5HFAjFNrWh+K1T2BOLNQZaZ xOQmTgOq1zoaLwNT40NdXd4= X-Google-Smtp-Source: ABdhPJzZJWrmdNiq23vSSEx1WKyiuXDANDMHJ1nEKgrpWX1VlxFg85RjNPR8ybTu5YzE5+qXGzBBLw== X-Received: by 2002:ac8:6ec2:: with SMTP id f2mr35754855qtv.159.1600460951789; Fri, 18 Sep 2020 13:29:11 -0700 (PDT) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id v2sm2805612qkv.26.2020.09.18.13.29.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Sep 2020 13:29:11 -0700 (PDT) Sender: Arvind Sankar From: Arvind Sankar X-Google-Original-From: Arvind Sankar Date: Fri, 18 Sep 2020 16:29:09 -0400 To: Linus Torvalds Cc: Matthew Wilcox , "Gustavo A. R. Silva" , Dennis Zhou , Tejun Heo , Christoph Lameter , Linux-MM , Linux Kernel Mailing List , Kees Cook Subject: Re: [GIT PULL] percpu fix for v5.9-rc6 Message-ID: <20200918202909.GA2946008@rani.riverdale.lan> References: <20200917204514.GA2880159@google.com> <20200918162305.GB25599@embeddedor> <20200918193426.GA15213@embeddedor> <20200918200252.GH32101@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 18, 2020 at 01:14:54PM -0700, Linus Torvalds wrote: > On Fri, Sep 18, 2020 at 1:02 PM Matthew Wilcox wrote: > > > > I suppose it's not really necessary, we could do offsetof here, right? > > Yup, that would make a lot more sense. > > But right now, the sizeof() obviously silently works. In general (i.e. outside the implementation of the macro itself), what is the preferred way of getting the size of just the header? 1) offsetof(typeof(s),flex) 2) struct_size(s, flex, 0) 3) sizeof(s) 4) new macro that's easier to read than 1 or 2, but makes it clear what you're doing?