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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 5D4F4C3A5A6 for ; Thu, 19 Sep 2019 14:48:53 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 29D80205F4 for ; Thu, 19 Sep 2019 14:48:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 29D80205F4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45120 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iAxjn-0007S3-Ol for qemu-devel@archiver.kernel.org; Thu, 19 Sep 2019 10:48:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58005) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iAxgG-0004to-Am for qemu-devel@nongnu.org; Thu, 19 Sep 2019 10:45:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iAxfi-0008Cr-Ds for qemu-devel@nongnu.org; Thu, 19 Sep 2019 10:44:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47013) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iAxfg-0008Bp-5S; Thu, 19 Sep 2019 10:44:36 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 26D7118C427A; Thu, 19 Sep 2019 14:44:35 +0000 (UTC) Received: from [10.3.116.249] (ovpn-116-249.phx2.redhat.com [10.3.116.249]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2FBDA10018F8; Thu, 19 Sep 2019 14:44:15 +0000 (UTC) Subject: Re: [RFC] error: auto propagated local_err To: Vladimir Sementsov-Ogievskiy , Kevin Wolf References: <20190918130244.24257-1-vsementsov@virtuozzo.com> <20190919091720.GB10163@localhost.localdomain> <57483252-273c-4606-47a8-eddeb840109a@redhat.com> <35c972e1-bdb5-cbcb-ed45-6a51f19af98c@virtuozzo.com> <696673be-95c8-3f75-551c-26fccd230eb1@virtuozzo.com> From: Eric Blake Openpgp: preference=signencrypt Autocrypt: addr=eblake@redhat.com; keydata= xsBNBEvHyWwBCACw7DwsQIh0kAbUXyqhfiKAKOTVu6OiMGffw2w90Ggrp4bdVKmCaEXlrVLU xphBM8mb+wsFkU+pq9YR621WXo9REYVIl0FxKeQo9dyQBZ/XvmUMka4NOmHtFg74nvkpJFCD TUNzmqfcjdKhfFV0d7P/ixKQeZr2WP1xMcjmAQY5YvQ2lUoHP43m8TtpB1LkjyYBCodd+LkV GmCx2Bop1LSblbvbrOm2bKpZdBPjncRNob73eTpIXEutvEaHH72LzpzksfcKM+M18cyRH+nP sAd98xIbVjm3Jm4k4d5oQyE2HwOur+trk2EcxTgdp17QapuWPwMfhaNq3runaX7x34zhABEB AAHNHkVyaWMgQmxha2UgPGVibGFrZUByZWRoYXQuY29tPsLAegQTAQgAJAIbAwULCQgHAwUV CgkICwUWAgMBAAIeAQIXgAUCS8fL9QIZAQAKCRCnoWtKJSdDahBHCACbl/5FGkUqJ89GAjeX RjpAeJtdKhujir0iS4CMSIng7fCiGZ0fNJCpL5RpViSo03Q7l37ss+No+dJI8KtAp6ID+PMz wTJe5Egtv/KGUKSDvOLYJ9WIIbftEObekP+GBpWP2+KbpADsc7EsNd70sYxExD3liwVJYqLc Rw7so1PEIFp+Ni9A1DrBR5NaJBnno2PHzHPTS9nmZVYm/4I32qkLXOcdX0XElO8VPDoVobG6 gELf4v/vIImdmxLh/w5WctUpBhWWIfQDvSOW2VZDOihm7pzhQodr3QP/GDLfpK6wI7exeu3P pfPtqwa06s1pae3ad13mZGzkBdNKs1HEm8x6zsBNBEvHyWwBCADGkMFzFjmmyqAEn5D+Mt4P zPdO8NatsDw8Qit3Rmzu+kUygxyYbz52ZO40WUu7EgQ5kDTOeRPnTOd7awWDQcl1gGBXgrkR pAlQ0l0ReO57Q0eglFydLMi5bkwYhfY+TwDPMh3aOP5qBXkm4qIYSsxb8A+i00P72AqFb9Q7 3weG/flxSPApLYQE5qWGSXjOkXJv42NGS6o6gd4RmD6Ap5e8ACo1lSMPfTpGzXlt4aRkBfvb NCfNsQikLZzFYDLbQgKBA33BDeV6vNJ9Cj0SgEGOkYyed4I6AbU0kIy1hHAm1r6+sAnEdIKj cHi3xWH/UPrZW5flM8Kqo14OTDkI9EtlABEBAAHCwF8EGAEIAAkFAkvHyWwCGwwACgkQp6Fr SiUnQ2q03wgAmRFGDeXzc58NX0NrDijUu0zx3Lns/qZ9VrkSWbNZBFjpWKaeL1fdVeE4TDGm I5mRRIsStjQzc2R9b+2VBUhlAqY1nAiBDv0Qnt+9cLiuEICeUwlyl42YdwpmY0ELcy5+u6wz mK/jxrYOpzXKDwLq5k4X+hmGuSNWWAN3gHiJqmJZPkhFPUIozZUCeEc76pS/IUN72NfprZmF Dp6/QDjDFtfS39bHSWXKVZUbqaMPqlj/z6Ugk027/3GUjHHr8WkeL1ezWepYDY7WSoXwfoAL 2UXYsMAr/uUncSKlfjvArhsej0S4zbqim2ZY6S8aRWw94J3bSvJR+Nwbs34GPTD4Pg== Organization: Red Hat, Inc. Message-ID: <152afb5b-8efb-d968-d595-94f58ad02a04@redhat.com> Date: Thu, 19 Sep 2019 09:44:14 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <696673be-95c8-3f75-551c-26fccd230eb1@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.62]); Thu, 19 Sep 2019 14:44:35 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "fam@euphon.net" , "peter.maydell@linaro.org" , "mst@redhat.com" , "codyprime@gmail.com" , "mark.cave-ayland@ilande.co.uk" , "qemu-devel@nongnu.org" , "armbru@redhat.com" , "kraxel@redhat.com" , "mreitz@redhat.com" , "qemu-block@nongnu.org" , "quintela@redhat.com" , "david@redhat.com" , "mdroth@linux.vnet.ibm.com" , "pasic@linux.ibm.com" , "borntraeger@de.ibm.com" , "marcandre.lureau@redhat.com" , "rth@twiddle.net" , "farman@linux.ibm.com" , "groug@kaod.org" , "dgilbert@redhat.com" , "alex.williamson@redhat.com" , "qemu-arm@nongnu.org" , "stefanha@redhat.com" , "jsnow@redhat.com" , "david@gibson.dropbear.id.au" , "berrange@redhat.com" , "cohuck@redhat.com" , "qemu-s390x@nongnu.org" , "sundeep.lkml@gmail.com" , "qemu-ppc@nongnu.org" , "pbonzini@redhat.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/19/19 9:30 AM, Vladimir Sementsov-Ogievskiy wrote: >> >> To the same topic, of minimization: should we always call MAKE_ERRP_SAFE at function top, or only >> in block, where it is needed (assume, we dereference it only inside some "if" or "while"? >> Kevin, is something bad in propagation, when it not related to error_abort? >> >> > > Or, even, we may use MAKE_ERRP_SAFE on every function, which have Error **errp argument, even if we neither > dereference it nor append hints? Is it what you propose by "SINGLE paradigm"? It's of course simpler to script, > to check in checkpatch and to maintain. Yes. The simpler we make the rules, and the less boilerplate it entails, the more likely that we can: a) avoid exceptions and corner cases that cost review time b) automate the conversion into complying with the rule c) codify those rules in syntax check to ensure they are followed post-conversion ALWAYS using MAKE_ERRP_SAFE() on entry to any function that has an Error **errp parameter is dirt-simple to explain. It has no performance penalty if the user passed in a normal error or error_abort (the cost of an 'if' hidden in the macro is probably negligible compared to everything else we do), and has no semantic penalty if the user passed in NULL or error_fatal (we now get the behavior we want with less boilerplate). Having to think 'does this method require me to use MAKE_ERRP_SAFE, or can I omit it?' does not provide the same simplicity. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org