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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 0AA40C352AA for ; Tue, 1 Oct 2019 16:53:23 +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 D76D42168B for ; Tue, 1 Oct 2019 16:53:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D76D42168B 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]:45018 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFLOr-0003pl-Gj for qemu-devel@archiver.kernel.org; Tue, 01 Oct 2019 12:53:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54001) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFKqx-0000bF-95 for qemu-devel@nongnu.org; Tue, 01 Oct 2019 12:18:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iFKqw-0005G2-0l for qemu-devel@nongnu.org; Tue, 01 Oct 2019 12:18:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34422) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iFKqq-00058z-4M; Tue, 01 Oct 2019 12:18:12 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8B72F3082231; Tue, 1 Oct 2019 16:18:10 +0000 (UTC) Received: from [10.3.116.201] (ovpn-116-201.phx2.redhat.com [10.3.116.201]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F19FF614CD; Tue, 1 Oct 2019 16:17:50 +0000 (UTC) Subject: Re: [PATCH v4 04/31] error: auto propagated local_err To: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org References: <20191001155319.8066-1-vsementsov@virtuozzo.com> <20191001155319.8066-5-vsementsov@virtuozzo.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Tue, 1 Oct 2019 11:17:50 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 MIME-Version: 1.0 In-Reply-To: <20191001155319.8066-5-vsementsov@virtuozzo.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Tue, 01 Oct 2019 16:18:11 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] 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, pburton@wavecomp.com, peter.maydell@linaro.org, codyprime@gmail.com, jasowang@redhat.com, mark.cave-ayland@ilande.co.uk, mdroth@linux.vnet.ibm.com, kraxel@redhat.com, sundeep.lkml@gmail.com, qemu-block@nongnu.org, quintela@redhat.com, arikalo@wavecomp.com, mst@redhat.com, armbru@redhat.com, pasic@linux.ibm.com, borntraeger@de.ibm.com, joel@jms.id.au, marcandre.lureau@redhat.com, rth@twiddle.net, farman@linux.ibm.com, ehabkost@redhat.com, sw@weilnetz.de, groug@kaod.org, yuval.shaia@oracle.com, dgilbert@redhat.com, alex.williamson@redhat.com, qemu-arm@nongnu.org, clg@kaod.org, stefanha@redhat.com, david@redhat.com, jsnow@redhat.com, david@gibson.dropbear.id.au, kwolf@redhat.com, integration@gluster.org, berrange@redhat.com, andrew@aj.id.au, cohuck@redhat.com, qemu-s390x@nongnu.org, mreitz@redhat.com, qemu-ppc@nongnu.org, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/1/19 10:52 AM, Vladimir Sementsov-Ogievskiy wrote: > Here is introduced ERRP_AUTO_PROPAGATE macro, to be used at start of > functions with errp OUT parameter. > > It has three goals: > > 1. Fix issue with error_fatal & error_prepend/error_append_hint: user > can't see this additional information, because exit() happens in > error_setg earlier than information is added. [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 > --- I'm still hoping Markus gets some review time for this series with a chance to speak up (and that we haven't been causing you a lot of work which would all have to change if Markus has a different viewpoint). Reviewed-by: Eric Blake > +/* > + * ERRP_AUTO_PROPAGATE > + * > + * This macro is created to be the first line of a function with Error **errp > + * OUT parameter. It's needed only in cases where we want to use error_prepend, > + * error_append_hint or dereference *errp. It's still safe (but useless) in > + * other cases. > + * > + * 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) Maybe: 'to append information (by error_prepend or 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_AUTO_PROPAGATE() \ > +g_auto(ErrorPropagator) __auto_errp_prop = {.errp = errp}; \ > +errp = ((errp == NULL || *errp == error_fatal) ? \ > + &__auto_errp_prop.local_err : errp) > + > /* > * Special error destination to abort on error. > * See error_setg() and error_propagate() for details. > -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org