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=-5.5 required=3.0 tests=BAYES_00, 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 D7D16C4363D for ; Fri, 25 Sep 2020 13:34:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF208206D4 for ; Fri, 25 Sep 2020 13:34:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728994AbgIYNeS (ORCPT ); Fri, 25 Sep 2020 09:34:18 -0400 Received: from foss.arm.com ([217.140.110.172]:45862 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728893AbgIYNeA (ORCPT ); Fri, 25 Sep 2020 09:34:00 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B12AB11B3; Fri, 25 Sep 2020 06:33:59 -0700 (PDT) Received: from [10.37.12.53] (unknown [10.37.12.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EB5953F73B; Fri, 25 Sep 2020 06:33:56 -0700 (PDT) Subject: Re: [PATCH v3 24/39] arm64: mte: Add in-kernel MTE helpers To: Catalin Marinas Cc: Andrey Konovalov , Dmitry Vyukov , kasan-dev@googlegroups.com, Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Elena Petrova , Branislav Rankov , Kevin Brodsky , Will Deacon , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20200925101558.GB4846@gaia> <20200925125059.GM4846@gaia> From: Vincenzo Frascino Message-ID: Date: Fri, 25 Sep 2020 14:36:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200925125059.GM4846@gaia> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/25/20 1:50 PM, Catalin Marinas wrote: >>>> + */ >>>> +SYM_FUNC_START(mte_assign_mem_tag_range) >>>> + /* if (src == NULL) return; */ >>>> + cbz x0, 2f >>>> + /* if (size == 0) return; */ >>>> + cbz x1, 2f >>> I find these checks unnecessary, as I said a couple of times before, >>> just document the function pre-conditions. They are also incomplete >>> (i.e. you check for NULL but not alignment). >>> >> I thought we agreed to harden the code further, based on [1]. Maybe I >> misunderstood. I am going to remove them and extend the comment in the next version. >> >> [1] >> https://lore.kernel.org/linux-arm-kernel/921c4ed0-b5b5-bc01-5418-c52d80f1af59@arm.com/ > Well, you concluded that but I haven't confirmed ;). Since it's called > from a single place which does the checks already, I don't see the point > in duplicating them. Documenting should be sufficient. Have you ever heard about "tacit consent"? ;) Anw, fine by me, I will add a comment here. -- Regards, Vincenzo