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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59522 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCRND-00056F-69 for qemu-devel@archiver.kernel.org; Mon, 23 Sep 2019 12:39:39 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57114) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCQxP-0002RP-27 for qemu-devel@nongnu.org; Mon, 23 Sep 2019 12:13:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iCQxM-0003jP-VF for qemu-devel@nongnu.org; Mon, 23 Sep 2019 12:12:58 -0400 Received: from relay.sw.ru ([185.231.240.75]:39522) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iCQxM-0003aE-IE; Mon, 23 Sep 2019 12:12:56 -0400 Received: from [10.94.3.0] (helo=kvm.qa.sw.ru) by relay.sw.ru with esmtp (Exim 4.92.2) (envelope-from ) id 1iCQwy-0001Fp-8L; Mon, 23 Sep 2019 19:12:32 +0300 From: Vladimir Sementsov-Ogievskiy To: qemu-devel@nongnu.org Subject: [RFC v2 1/9] error: auto propagated local_err Date: Mon, 23 Sep 2019 19:12:23 +0300 Message-Id: <20190923161231.22028-2-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190923161231.22028-1-vsementsov@virtuozzo.com> References: <20190923161231.22028-1-vsementsov@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 185.231.240.75 X-Mailman-Approved-At: Mon, 23 Sep 2019 12:26:10 -0400 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: stefanha@redhat.com, codyprime@gmail.com, jan.kiszka@siemens.com, berto@igalia.com, zhang.zhanghailiang@huawei.com, qemu-block@nongnu.org, arikalo@wavecomp.com, pasic@linux.ibm.com, hpoussin@reactos.org, anthony.perard@citrix.com, samuel.thibault@ens-lyon.org, philmd@redhat.com, green@moxielogic.com, lvivier@redhat.com, ehabkost@redhat.com, xiechanglong.d@gmail.com, pl@kamp.de, dgilbert@redhat.com, b.galvani@gmail.com, eric.auger@redhat.com, alex.williamson@redhat.com, ronniesahlberg@gmail.com, jsnow@redhat.com, rth@twiddle.net, kwolf@redhat.com, vsementsov@virtuozzo.com, andrew@aj.id.au, crwulff@gmail.com, sundeep.lkml@gmail.com, michael@walle.cc, qemu-ppc@nongnu.org, kbastian@mail.uni-paderborn.de, imammedo@redhat.com, fam@euphon.net, peter.maydell@linaro.org, sheepdog@lists.wpkg.org, david@redhat.com, palmer@sifive.com, thuth@redhat.com, jcmvbkbc@gmail.com, den@openvz.org, hare@suse.com, sstabellini@kernel.org, arei.gonglei@huawei.com, namei.unix@gmail.com, atar4qemu@gmail.com, farman@linux.ibm.com, amit@kernel.org, sw@weilnetz.de, groug@kaod.org, qemu-s390x@nongnu.org, qemu-arm@nongnu.org, peter.chubb@nicta.com.au, clg@kaod.org, shorne@gmail.com, qemu-riscv@nongnu.org, cohuck@redhat.com, amarkovic@wavecomp.com, aurelien@aurel32.net, pburton@wavecomp.com, sagark@eecs.berkeley.edu, jasowang@redhat.com, kraxel@redhat.com, edgar.iglesias@gmail.com, gxt@mprc.pku.edu.cn, ari@tuxera.com, quintela@redhat.com, mdroth@linux.vnet.ibm.com, lersek@redhat.com, borntraeger@de.ibm.com, antonynpavlov@gmail.com, dillaman@redhat.com, joel@jms.id.au, xen-devel@lists.xenproject.org, integration@gluster.org, rjones@redhat.com, Andrew.Baumann@microsoft.com, mreitz@redhat.com, walling@linux.ibm.com, mst@redhat.com, mark.cave-ayland@ilande.co.uk, v.maffione@gmail.com, marex@denx.de, armbru@redhat.com, marcandre.lureau@redhat.com, alistair@alistair23.me, paul.durrant@citrix.com, pavel.dovgaluk@ispras.ru, g.lettieri@iet.unipi.it, rizzo@iet.unipi.it, david@gibson.dropbear.id.au, akrowiak@linux.ibm.com, berrange@redhat.com, xiaoguangrong.eric@gmail.com, pmorel@linux.ibm.com, wencongyang2@huawei.com, jcd@tribudubois.net, pbonzini@redhat.com, stefanb@linux.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Here is introduced ERRP_FUNCTION_BEGIN macro, to be used at start of any function 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 don'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 should be merely updated to return int error code). Signed-off-by: Vladimir Sementsov-Ogievskiy --- include/qapi/error.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/include/qapi/error.h b/include/qapi/error.h index 3f95141a01..f6f4fa0fac 100644 --- a/include/qapi/error.h +++ b/include/qapi/error.h @@ -322,6 +322,43 @@ void error_set_internal(Error **errp, ErrorClass err_class, const char *fmt, ...) GCC_FMT_ATTR(6, 7); +typedef struct ErrorPropagator { + Error *local_err; + Error **errp; +} ErrorPropagator; + +static inline void error_propagator_cleanup(ErrorPropagator *prop) +{ + error_propagate(prop->errp, prop->local_err); +} + +G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(ErrorPropagator, error_propagator_cleanup); + +/* + * ERRP_FUNCTION_BEGIN + * + * This macro MUST be the first line of EACH function with Error **errp + * parameter. + * + * If errp is NULL or points to error_fatal, it is rewritten to point to + * local Error object, which will be automatically propagated to 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 hint (by error_append_hint) + * (as, if it was error_fatal, we swapped it by local_error to be + * propagated on cleanup). + * + * Note: we don't wrap 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}; \ +Error **__local_errp_unused __attribute__ ((unused)) = \ + (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. -- 2.21.0