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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 38AE7C432C2 for ; Tue, 24 Sep 2019 20:53:54 +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 0470A207FD for ; Tue, 24 Sep 2019 20:53:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0470A207FD 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]:51102 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCrom-0005N1-N2 for qemu-devel@archiver.kernel.org; Tue, 24 Sep 2019 16:53:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53269) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCrhN-0006Ue-3h for qemu-devel@nongnu.org; Tue, 24 Sep 2019 16:46:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iCrhL-0006Dt-C2 for qemu-devel@nongnu.org; Tue, 24 Sep 2019 16:46:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47436) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iCrhF-0006BH-PL; Tue, 24 Sep 2019 16:46:05 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A43738535C; Tue, 24 Sep 2019 20:46:04 +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 35BCA5D721; Tue, 24 Sep 2019 20:46:01 +0000 (UTC) Subject: Re: [PATCH v3 04/25] error: auto propagated local_err To: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org References: <20190924200902.4703-1-vsementsov@virtuozzo.com> <20190924200902.4703-5-vsementsov@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: <329dc766-b052-e35c-c709-84d3fd1af0f7@redhat.com> Date: Tue, 24 Sep 2019 15:46:00 -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: <20190924200902.4703-5-vsementsov@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 24 Sep 2019 20:46:05 +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 Zheng , Paul Burton , Peter Maydell , Jeff Cody , Jason Wang , Mark Cave-Ayland , Michael Roth , Gerd Hoffmann , Subbaraya Sundeep , qemu-block@nongnu.org, Juan Quintela , Aleksandar Rikalo , "Michael S. Tsirkin" , Markus Armbruster , Halil Pasic , Christian Borntraeger , =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , David Gibson , Eric Farman , Eduardo Habkost , Greg Kurz , Yuval Shaia , "Dr. David Alan Gilbert" , Alex Williamson , qemu-arm@nongnu.org, David Hildenbrand , John Snow , Richard Henderson , Kevin Wolf , integration@gluster.org, =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Cornelia Huck , qemu-s390x@nongnu.org, Max Reitz , qemu-ppc@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/24/19 3:08 PM, Vladimir Sementsov-Ogievskiy wrote: > Here is introduced ERRP_FUNCTION_BEGIN macro, to be used at start of > functions with errp parameter. > > It has three goals: > > 1. Fix issue with error_fatal & error_append_hint: user can't see these > hints, because exit() happens in error_setg earlier than hint is > appended. [Reported by Greg Kurz] > > 2. Fix issue with error_abort & error_propagate: when we wrap > error_abort by local_err+error_propagate, resulting coredump will > refer to error_propagate and not to the place where error happened. > (the macro itself doesn't fix the issue, but it allows to [3.] drop all > local_err+error_propagate pattern, which will definitely fix the issue) > [Reported by Kevin Wolf] > > 3. Drop local_err+error_propagate pattern, which is used to workaround > void functions with errp parameter, when caller wants to know resulting > status. (Note: actually these functions could be merely updated to > return int error code). > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > > +/* > + * ERRP_FUNCTION_BEGIN > + * > + * This macro is created to be the first line of a function with Error **errp > + * parameter. Since you're going with the reduced scope of only touching functions with error_append_hint, we may want to tweak this sentence to call out only the functions that REQUIRE the use of this macro (if they contain *errp or error_apend_hint), while mentioning that it is still safe to use on any function with an errp parameter. I'm hoping Markus will be able to chime in with his preferences soon. > + * > + * If errp is NULL or points to error_fatal, it is rewritten to point to a > + * local Error object, which will be automatically propagated to the original > + * errp on function exit (see error_propagator_cleanup). > + * > + * After invocation of this macro it is always safe to dereference errp > + * (as it's not NULL anymore) and to append hints (by error_append_hint) > + * (as, if it was error_fatal, we swapped it with a local_error to be > + * propagated on cleanup). > + * > + * Note: we don't wrap the error_abort case, as we want resulting coredump > + * to point to the place where the error happened, not to error_propagate. > + */ > +#define ERRP_FUNCTION_BEGIN() \ > +g_auto(ErrorPropagator) __auto_errp_prop = {.errp = errp}; \ > +errp = ((errp == NULL || *errp == error_fatal) ? \ > + &__auto_errp_prop.local_err : errp) > + Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org