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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 61695C433ED for ; Wed, 19 May 2021 13:37:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C9CDB610A8 for ; Wed, 19 May 2021 13:37:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C9CDB610A8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4BCE26B0036; Wed, 19 May 2021 09:37:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4962F6B006E; Wed, 19 May 2021 09:37:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 30D8C6B0070; Wed, 19 May 2021 09:37:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0237.hostedemail.com [216.40.44.237]) by kanga.kvack.org (Postfix) with ESMTP id 014056B0036 for ; Wed, 19 May 2021 09:37:48 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 9D75C8158 for ; Wed, 19 May 2021 13:37:48 +0000 (UTC) X-FDA: 78158083416.11.CBE5D09 Received: from mail-qv1-f42.google.com (mail-qv1-f42.google.com [209.85.219.42]) by imf22.hostedemail.com (Postfix) with ESMTP id A78F4C0007E8 for ; Wed, 19 May 2021 13:37:47 +0000 (UTC) Received: by mail-qv1-f42.google.com with SMTP id ee9so6750641qvb.8 for ; Wed, 19 May 2021 06:37:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=YWIRPlMK16+RzCykbPBcngvEk4WSCNCvsGMUpXzHNrs=; b=YzZGNzRNmp4WdmSOxPiKo2tqmXM1FnA+cZr3Q6v9sCPpmvCgbmagVhwQrPPTWubwxf 8bwWpUSBYp6rOAJu5tQRJQ0ylbrW16/0oPEAwP5lg2pbE0mOJk9vkgL/S5OQnyMHOZsY eFKg+bEwbr9CpSqLXfYWvqNssPDRHG7xuj6ovwlc87/Yti/H4W560vFUNaoupEv8x/3U dXHGxjLkLJt3TU7EGfB5AZAPd/43Ae3jAAU4M7ted4iF0ryCsK034dpuwcfRwSUJAVnf 9cgjUQZP50gCPvF4ny+cGfWhnwPzRNd+s+Gfp6oTBkXCx2EHMJCahuF+Rjz7nNEQCsbr CsVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:subject:to:cc:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=YWIRPlMK16+RzCykbPBcngvEk4WSCNCvsGMUpXzHNrs=; b=Lc3fHmVOEupnBHTTs+prXG4SPNHKH6wGhSnewG/HZoU/eqvO88YZUXbV0meLR04zBt tV3um6Bzjdp+dktL2BWH7XAkEjNgGh1ImmUo+opDLmt0YkEVr6kSIWGY3wzx9TbOZrsl H240X3wn4LFPvMhTrUwrC0oGM7AZVfnDGuhRLjZzFC1u7xqRR7Dy2lp6kmc8q7/ww3t0 PnEL6adIhff6JRhey6BbmYs0t/jTLK886Oie3QDWtVbQ78UC5ygfEa+b1rwUDfH7wLj6 2atODkrhfENYCPX+5g4U9k8um5pcJSdHQlnXz5lBwNvqNo88kghbZ8KqEngWRSTTS0Hn RMVQ== X-Gm-Message-State: AOAM532WD+Umt/tXbTS5GHk/+xAoMtxAsr7VNp3UoTZIw2KZfHv0QBIT iSf+pW/vPPdCEHebtfj2qzM= X-Google-Smtp-Source: ABdhPJzaGN1oVVL29Ii9MlO6gyKUOEJPHBzF/3Jb4R5JFVqKi8U7chULNKkp8uI592WGsyY4nnqeaw== X-Received: by 2002:a0c:b292:: with SMTP id r18mr13102237qve.57.1621431467692; Wed, 19 May 2021 06:37:47 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id q13sm15436194qkj.43.2021.05.19.06.37.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 May 2021 06:37:47 -0700 (PDT) Subject: Re: [PATCH v5 5/9] powerpc/mm/book3s64: Update tlb flush routines to take a page walk cache flush argument To: Segher Boessenkool , Michael Ellerman Cc: "Aneesh Kumar K.V" , npiggin@gmail.com, linux-mm@kvack.org, kaleshsingh@google.com, joel@joelfernandes.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org References: <20210422054323.150993-1-aneesh.kumar@linux.ibm.com> <20210422054323.150993-6-aneesh.kumar@linux.ibm.com> <20210515163525.GA1106462@roeck-us.net> <87pmxpqxb1.fsf@linux.ibm.com> <87a6ork1qp.fsf@mpe.ellerman.id.au> <20210519004514.GC10366@gate.crashing.org> <20210519120306.GD10366@gate.crashing.org> From: Guenter Roeck Message-ID: <46cedc01-bca7-236d-9f74-a9cc24391512@roeck-us.net> Date: Wed, 19 May 2021 06:37:44 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210519120306.GD10366@gate.crashing.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=YzZGNzRN; spf=pass (imf22.hostedemail.com: domain of groeck7@gmail.com designates 209.85.219.42 as permitted sender) smtp.mailfrom=groeck7@gmail.com; dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: A78F4C0007E8 X-Stat-Signature: ia7zmji64kqui4u35seyx5xxsii6afkf X-HE-Tag: 1621431467-532052 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 5/19/21 5:03 AM, Segher Boessenkool wrote: > On Tue, May 18, 2021 at 07:45:14PM -0500, Segher Boessenkool wrote: >> On Wed, May 19, 2021 at 10:26:22AM +1000, Michael Ellerman wrote: >>> Guenter Roeck writes: >>>> Ah, sorry. I wasn't aware that the following is valid C code >>>> >>>> void f1() >>>> { >>>> return f2(); >>>> ^^^^^^ >>>> } >>>> >>>> as long as f2() is void as well. Confusing, but we live and learn. >>> >>> It might be valid, but it's still bad IMHO. >>> >>> It's confusing to readers, and serves no useful purpose. >> >> And it actually explicitly is undefined behaviour in C90 already >> (3.6.6.4 in C90, 6.8.6.4 in C99 and later). > > ... but there is a GCC extension that allows this by default: > > For C only, warn about a 'return' statement with an expression in a > function whose return type is 'void', unless the expression type is > also 'void'. As a GNU extension, the latter case is accepted > without a warning unless '-Wpedantic' is used. > In C99: "6.8.6.4 The return statement Constraints A return statement with an expression shall not appear in a function whose return type is void. A return statement without an expression shall only appear in a function whose return type is void." Sounds like invalid to me, not just undefined behavior. Guenter