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[209.51.188.17]) by mx.google.com with ESMTPS id v69si10376092qkb.164.2019.09.30.09.39.50 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 30 Sep 2019 09:39:50 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from localhost ([::1]:54982 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iEyiD-0007in-M6 for alex.bennee@linaro.org; Mon, 30 Sep 2019 12:39:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43021) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iEyi4-0007ib-Uj for qemu-arm@nongnu.org; Mon, 30 Sep 2019 12:39:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iEyi2-0007Bb-8s for qemu-arm@nongnu.org; Mon, 30 Sep 2019 12:39:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46162) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iEyi2-0007B6-05; Mon, 30 Sep 2019 12:39:38 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 51EF010CC1F4; Mon, 30 Sep 2019 16:39:36 +0000 (UTC) Received: from linux.fritz.box (ovpn-116-86.ams2.redhat.com [10.36.116.86]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9728B5D9CA; Mon, 30 Sep 2019 16:39:10 +0000 (UTC) Date: Mon, 30 Sep 2019 18:39:09 +0200 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v3 04/25] error: auto propagated local_err Message-ID: <20190930163909.GD12777@linux.fritz.box> References: <20190924200902.4703-1-vsementsov@virtuozzo.com> <20190924200902.4703-5-vsementsov@virtuozzo.com> <20190930151215.GB12777@linux.fritz.box> <20190930160039.GC12777@linux.fritz.box> <495102b2-5d1a-f659-4387-5733ae34b3e2@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <495102b2-5d1a-f659-4387-5733ae34b3e2@virtuozzo.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.65]); Mon, 30 Sep 2019 16:39:36 +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-arm@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 , Peter Maydell , Paul Burton , Jeff Cody , Jason Wang , Mark Cave-Ayland , "qemu-devel@nongnu.org" , Michael Roth , Gerd Hoffmann , Subbaraya Sundeep , Eric Blake , "qemu-block@nongnu.org" , Juan Quintela , Aleksandar Rikalo , "Michael S. Tsirkin" , Markus Armbruster , Halil Pasic , Christian Borntraeger , Marcel Apfelbaum , =?iso-8859-1?Q?Marc-Andr=E9?= 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 , "integration@gluster.org" , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Cornelia Huck , "qemu-s390x@nongnu.org" , Max Reitz , "qemu-ppc@nongnu.org" , Paolo Bonzini Errors-To: qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-arm" X-TUID: oZptccyTRoif Am 30.09.2019 um 18:26 hat Vladimir Sementsov-Ogievskiy geschrieben: > 30.09.2019 19:00, Kevin Wolf wrote: > > Am 30.09.2019 um 17:19 hat Vladimir Sementsov-Ogievskiy geschrieben: > >> 30.09.2019 18:12, Kevin Wolf wrote: > >>> Am 24.09.2019 um 22:08 hat Vladimir Sementsov-Ogievskiy geschrieben: > >>>> Here is introduced ERRP_FUNCTION_BEGIN macro, to be used at start of > >>>> functions with errp parameter. > >>> > >>> A bit of bike shedding, but FOO_BEGIN suggests to me that a FOO_END will > >>> follow. Can we find a different name, especially now that we won't use > >>> this macro in every function that uses an errp, so even the "errp > >>> function" part isn't really correct any more? > >>> > >>> How about ERRP_AUTO_PROPAGATE? > >> > >> I have an idea that with this macro we can (optionally) get the whole call stack > >> of the error and print it to log, so it's good to give it more generic name, not > >> limited to propagation.. > > > > Hm, what's the context for this feature? > > > > The obvious one where you want to have a stack trace is &error_abort, > > but that one crashes, so you get it automatically. If it's just a normal > > error (like a QAPI option contains an invalid value and some function > > down the call chain checks it), why would anyone want to know what the > > call chain in the QEMU code was? > > > > When I have bug from testers, call stack would be a lot more descriptive, than just > an error message. > > We may add trace point which will print this information, so with disabled trace point > - no extra output. But wouldn't it make much more sense then to optionally add this functionality to any trace point? I really don't see how this is related specifically to user-visible error messages. However, even if we decide that we want to have this in Error objects, wouldn't it make much more sense to use the real C stack trace and save it from the innermost error_set() using backtrace() or compiler built-ins rather than relying on an error_propagate() chain? Kevin 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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 9E6EAC32792 for ; Mon, 30 Sep 2019 16:40:36 +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 717FB215EA for ; Mon, 30 Sep 2019 16:40:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 717FB215EA 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]:55000 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iEyix-00004z-Ki for qemu-devel@archiver.kernel.org; Mon, 30 Sep 2019 12:40:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43046) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iEyi9-0007lX-IA for qemu-devel@nongnu.org; Mon, 30 Sep 2019 12:39:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iEyi8-0007Dy-Em for qemu-devel@nongnu.org; Mon, 30 Sep 2019 12:39:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46162) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iEyi2-0007B6-05; Mon, 30 Sep 2019 12:39:38 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 51EF010CC1F4; Mon, 30 Sep 2019 16:39:36 +0000 (UTC) Received: from linux.fritz.box (ovpn-116-86.ams2.redhat.com [10.36.116.86]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9728B5D9CA; Mon, 30 Sep 2019 16:39:10 +0000 (UTC) Date: Mon, 30 Sep 2019 18:39:09 +0200 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v3 04/25] error: auto propagated local_err Message-ID: <20190930163909.GD12777@linux.fritz.box> References: <20190924200902.4703-1-vsementsov@virtuozzo.com> <20190924200902.4703-5-vsementsov@virtuozzo.com> <20190930151215.GB12777@linux.fritz.box> <20190930160039.GC12777@linux.fritz.box> <495102b2-5d1a-f659-4387-5733ae34b3e2@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <495102b2-5d1a-f659-4387-5733ae34b3e2@virtuozzo.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.65]); Mon, 30 Sep 2019 16:39:36 +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 Zheng , Peter Maydell , Paul Burton , Jeff Cody , Jason Wang , Mark Cave-Ayland , "qemu-devel@nongnu.org" , Michael Roth , Gerd Hoffmann , Subbaraya Sundeep , "qemu-block@nongnu.org" , Juan Quintela , Aleksandar Rikalo , "Michael S. Tsirkin" , Markus Armbruster , Halil Pasic , Christian Borntraeger , =?iso-8859-1?Q?Marc-Andr=E9?= 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 , "integration@gluster.org" , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , 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" Am 30.09.2019 um 18:26 hat Vladimir Sementsov-Ogievskiy geschrieben: > 30.09.2019 19:00, Kevin Wolf wrote: > > Am 30.09.2019 um 17:19 hat Vladimir Sementsov-Ogievskiy geschrieben: > >> 30.09.2019 18:12, Kevin Wolf wrote: > >>> Am 24.09.2019 um 22:08 hat Vladimir Sementsov-Ogievskiy geschrieben: > >>>> Here is introduced ERRP_FUNCTION_BEGIN macro, to be used at start of > >>>> functions with errp parameter. > >>> > >>> A bit of bike shedding, but FOO_BEGIN suggests to me that a FOO_END will > >>> follow. Can we find a different name, especially now that we won't use > >>> this macro in every function that uses an errp, so even the "errp > >>> function" part isn't really correct any more? > >>> > >>> How about ERRP_AUTO_PROPAGATE? > >> > >> I have an idea that with this macro we can (optionally) get the whole call stack > >> of the error and print it to log, so it's good to give it more generic name, not > >> limited to propagation.. > > > > Hm, what's the context for this feature? > > > > The obvious one where you want to have a stack trace is &error_abort, > > but that one crashes, so you get it automatically. If it's just a normal > > error (like a QAPI option contains an invalid value and some function > > down the call chain checks it), why would anyone want to know what the > > call chain in the QEMU code was? > > > > When I have bug from testers, call stack would be a lot more descriptive, than just > an error message. > > We may add trace point which will print this information, so with disabled trace point > - no extra output. But wouldn't it make much more sense then to optionally add this functionality to any trace point? I really don't see how this is related specifically to user-visible error messages. However, even if we decide that we want to have this in Error objects, wouldn't it make much more sense to use the real C stack trace and save it from the innermost error_set() using backtrace() or compiler built-ins rather than relying on an error_propagate() chain? Kevin