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=-6.3 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 A0CFAC433E0 for ; Wed, 29 Jul 2020 20:09:23 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 77D1320658 for ; Wed, 29 Jul 2020 20:09:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 77D1320658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k0sNw-00014Z-2C; Wed, 29 Jul 2020 20:09:08 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k0sNu-00014U-FM for xen-devel@lists.xenproject.org; Wed, 29 Jul 2020 20:09:06 +0000 X-Inumbo-ID: 5a5e63b2-d1d7-11ea-aa56-12813bfff9fa Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 5a5e63b2-d1d7-11ea-aa56-12813bfff9fa; Wed, 29 Jul 2020 20:09:05 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C2198AB55; Wed, 29 Jul 2020 20:09:16 +0000 (UTC) Subject: Re: [PATCH 3/5] xen/memory: Fix compat XENMEM_acquire_resource for size requests To: Andrew Cooper References: <20200728113712.22966-1-andrew.cooper3@citrix.com> <20200728113712.22966-4-andrew.cooper3@citrix.com> From: Jan Beulich Message-ID: <0c275cb5-55ec-b0b0-6ba8-cfa7ca23978b@suse.com> Date: Wed, 29 Jul 2020 22:09:06 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200728113712.22966-4-andrew.cooper3@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Hubert Jasudowicz , Stefano Stabellini , Julien Grall , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Paul Durrant , =?UTF-8?Q?Micha=c5=82_Leszczy=c5=84ski?= , Ian Jackson , Xen-devel Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 28.07.2020 13:37, Andrew Cooper wrote: > Copy the nr_frames from the correct structure, so the caller doesn't > unconditionally receive 0. Well, no - it does get copied from the correct structure. It's just that the field doesn't get set properly up front. Otherwise you'll (a) build in an unchecked assumption that the native and compat fields match in type and (b) set a bad example for people looking here and then cloning this code in perhaps a case where (a) is not even true. If you agree, the alternative change of setting cmp.mar.nr_frames from nat.mar->nr_frames before the call is Reviewed-by: Jan Beulich Jan