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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 07D46C433E0 for ; Wed, 20 Jan 2021 18:27:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 74855233FC for ; Wed, 20 Jan 2021 18:27:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74855233FC Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A52CE6B000A; Wed, 20 Jan 2021 13:27:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A02E66B000C; Wed, 20 Jan 2021 13:27:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F1396B000D; Wed, 20 Jan 2021 13:27:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0230.hostedemail.com [216.40.44.230]) by kanga.kvack.org (Postfix) with ESMTP id 769496B000A for ; Wed, 20 Jan 2021 13:27:17 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 3AD49180AD81F for ; Wed, 20 Jan 2021 18:27:17 +0000 (UTC) X-FDA: 77726985714.26.quill30_1b165462755c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin26.hostedemail.com (Postfix) with ESMTP id 72B2A1804B65C for ; Wed, 20 Jan 2021 18:27:16 +0000 (UTC) X-HE-Tag: quill30_1b165462755c X-Filterd-Recvd-Size: 5224 Received: from mail-pj1-f54.google.com (mail-pj1-f54.google.com [209.85.216.54]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Wed, 20 Jan 2021 18:27:15 +0000 (UTC) Received: by mail-pj1-f54.google.com with SMTP id y12so2689013pji.1 for ; Wed, 20 Jan 2021 10:27:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=uiW6R+4OroO7DV/CnGwFhudMKTgvqDzlldk0/NCSxIM=; b=quWaPHodtXoBEM4er9UrGLPUP4C6pIAo1GfMKNEJNcdOz4TFWyZR+oBy9LoOaUlFpl 8zpzY1PKROmbQwEOb7yvm8ggsN9fh0D1uwXu6rYsXh2rrh8Ae7WULfiPMhN/wy/nSRCI bC5+7Z4yH/Gwiini9VCTaujDniBcpQbsPaB6W5srOSFSJAZJq4HUPc9GyKumH2lLxyr3 20iZoVwN++wb61UullUjVK81Uk1yMkOgyxRPZrMBoFPKC/Pif8PM0GebcQCf9fh+YXJ0 VbKja2a8YxlBdC9zs8HV9JhEIVyR7e35k1j86OtY9JFvpJyNFWIHgdArmjw1XwzIwuJ9 x9Cw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uiW6R+4OroO7DV/CnGwFhudMKTgvqDzlldk0/NCSxIM=; b=az39JFugGCp4o2fmVOFQLNfp8WYonTJr1Xw/ufvQ/u3FilelA5eccop1am9sy9XsI1 y0aJ6G9+iBc8kDcXGCA2Vr1zJ65D5KmatmkCrHSGu/lrjvB2aa2aihYrLYzE6/qpYEIH CXglgt6fTCiO2BGlo/ywsZvdnyjS+i0z0q9s9mUsd5Ymz0iHlHhRCEghHayudHulTRRc 0VPQtyV4WwCBQtEcqnvtm9J87i+ojwNv26Lac7eqiL14oVdFspGd2ifIbCjTH7SdI6BU uf62W2kbC8LQMdp1P8bcXraVTXhwZ070iMaiOxIIqyp3C63oeUbKVCH6R/Eb9Yc3HLiV D55A== X-Gm-Message-State: AOAM533UwDnFeMytDUy2rermW+9/cttguVzIgitRsGDfGLuJBZPTYFep t7lorLlh2z2PTjW703uo3xYhX+XYhmSwGDhcEM9rhw== X-Google-Smtp-Source: ABdhPJztSwBi+iAIwUggUK6+sTeRb+j0bW0Cdtft+/KRMsHKFTPOr75taMb9vlVZxWG24rYXR0mZQzqMPzxZOXgDSK4= X-Received: by 2002:a17:902:26a:b029:da:af47:77c7 with SMTP id 97-20020a170902026ab02900daaf4777c7mr11275754plc.10.1611167234448; Wed, 20 Jan 2021 10:27:14 -0800 (PST) MIME-Version: 1.0 References: <20210120173612.20913-1-will@kernel.org> <20210120173612.20913-9-will@kernel.org> In-Reply-To: <20210120173612.20913-9-will@kernel.org> From: Nick Desaulniers Date: Wed, 20 Jan 2021 10:27:04 -0800 Message-ID: Subject: Re: [PATCH v4 8/8] mm: Mark anonymous struct field of 'struct vm_fault' as 'const' To: Will Deacon Cc: LKML , Linux Memory Management List , Linux ARM , Catalin Marinas , Jan Kara , Minchan Kim , Andrew Morton , "Kirill A . Shutemov" , Linus Torvalds , Vinayak Menon , Hugh Dickins , kernel-team Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jan 20, 2021 at 9:36 AM Will Deacon wrote: > > The fields of this struct are only ever read after being initialised, so > mark it 'const' before somebody tries to modify it again. > > Cc: Kirill A. Shutemov > Cc: Linus Torvalds > Signed-off-by: Will Deacon > --- > include/linux/mm.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index e0f056753bef..7ff3d9817d38 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -514,7 +514,7 @@ static inline bool fault_flag_allow_retry_first(unsigned int flags) > * pgoff should be used in favour of virtual_address, if possible. > */ > struct vm_fault { > - struct { > + const struct { > struct vm_area_struct *vma; /* Target VMA */ > gfp_t gfp_mask; /* gfp mask to be used for allocations */ > pgoff_t pgoff; /* Logical page offset based on vma */ Is there a difference between: + const struct { + struct vm_area_struct *vma; /* Target VMA */ + gfp_t gfp_mask; /* gfp mask to be used for allocations */ + pgoff_t pgoff; /* Logical page offset based on vma */ + unsigned long address; /* Faulting virtual address */ + }; vs + struct { + struct vm_area_struct * const vma; /* Target VMA */ + const gfp_t gfp_mask; /* gfp mask to be used for allocations */ + const pgoff_t pgoff; /* Logical page offset based on vma */ + const unsigned long address; /* Faulting virtual address */ + }; ie. marking the members const vs the anonymous struct? Does anything need to change in the use of these structures? > -- > 2.30.0.284.gd98b1dd5eaa7-goog > -- Thanks, ~Nick Desaulniers