Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> writes: > 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.
I get what you mean, but I have plenty of context. > (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) The parenthesis is not part of the goal. > [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). > > To achieve these goals, we need to add invocation of the macro at start > of functions, which needs error_prepend/error_append_hint (1.); add > invocation of the macro at start of functions which do > local_err+error_propagate scenario the check errors, drop local errors > from them and just use *errp instead (2., 3.). The paragraph talks about two cases: 1. and 2.+3. Makes me think we want two paragraphs, each illustrated with an example. What about you provide the examples, and then I try to polish the prose? > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > Reviewed-by: Eric Blake <ebl...@redhat.com> > --- > > CC: Gerd Hoffmann <kra...@redhat.com> > CC: "Gonglei (Arei)" <arei.gong...@huawei.com> > CC: Eduardo Habkost <ehabk...@redhat.com> > CC: Igor Mammedov <imamm...@redhat.com> > CC: Laurent Vivier <lviv...@redhat.com> > CC: Amit Shah <a...@kernel.org> > CC: Kevin Wolf <kw...@redhat.com> > CC: Max Reitz <mre...@redhat.com> > CC: John Snow <js...@redhat.com> > CC: Ari Sundholm <a...@tuxera.com> > CC: Pavel Dovgalyuk <pavel.dovga...@ispras.ru> > CC: Paolo Bonzini <pbonz...@redhat.com> > CC: Stefan Hajnoczi <stefa...@redhat.com> > CC: Fam Zheng <f...@euphon.net> > CC: Stefan Weil <s...@weilnetz.de> > CC: Ronnie Sahlberg <ronniesahlb...@gmail.com> > CC: Peter Lieven <p...@kamp.de> > CC: Eric Blake <ebl...@redhat.com> > CC: "Denis V. Lunev" <d...@openvz.org> > CC: Markus Armbruster <arm...@redhat.com> > CC: Alberto Garcia <be...@igalia.com> > CC: Jason Dillaman <dilla...@redhat.com> > CC: Wen Congyang <wencongya...@huawei.com> > CC: Xie Changlong <xiechanglon...@gmail.com> > CC: Liu Yuan <namei.u...@gmail.com> > CC: "Richard W.M. Jones" <rjo...@redhat.com> > CC: Jeff Cody <codypr...@gmail.com> > CC: "Marc-André Lureau" <marcandre.lur...@redhat.com> > CC: "Daniel P. Berrangé" <berra...@redhat.com> > CC: Richard Henderson <r...@twiddle.net> > CC: Greg Kurz <gr...@kaod.org> > CC: "Michael S. Tsirkin" <m...@redhat.com> > CC: Marcel Apfelbaum <marcel.apfelb...@gmail.com> > CC: Beniamino Galvani <b.galv...@gmail.com> > CC: Peter Maydell <peter.mayd...@linaro.org> > CC: "Cédric Le Goater" <c...@kaod.org> > CC: Andrew Jeffery <and...@aj.id.au> > CC: Joel Stanley <j...@jms.id.au> > CC: Andrew Baumann <andrew.baum...@microsoft.com> > CC: "Philippe Mathieu-Daudé" <phi...@redhat.com> > CC: Antony Pavlov <antonynpav...@gmail.com> > CC: Jean-Christophe Dubois <j...@tribudubois.net> > CC: Peter Chubb <peter.ch...@nicta.com.au> > CC: Subbaraya Sundeep <sundeep.l...@gmail.com> > CC: Eric Auger <eric.au...@redhat.com> > CC: Alistair Francis <alist...@alistair23.me> > CC: "Edgar E. Iglesias" <edgar.igles...@gmail.com> > CC: Stefano Stabellini <sstabell...@kernel.org> > CC: Anthony Perard <anthony.per...@citrix.com> > CC: Paul Durrant <p...@xen.org> > CC: Paul Burton <pbur...@wavecomp.com> > CC: Aleksandar Rikalo <arik...@wavecomp.com> > CC: Chris Wulff <crwu...@gmail.com> > CC: Marek Vasut <ma...@denx.de> > CC: David Gibson <da...@gibson.dropbear.id.au> > CC: Cornelia Huck <coh...@redhat.com> > CC: Halil Pasic <pa...@linux.ibm.com> > CC: Christian Borntraeger <borntrae...@de.ibm.com> > CC: "Hervé Poussineau" <hpous...@reactos.org> > CC: Xiao Guangrong <xiaoguangrong.e...@gmail.com> > CC: Aurelien Jarno <aurel...@aurel32.net> > CC: Aleksandar Markovic <amarko...@wavecomp.com> > CC: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk> > CC: Jason Wang <jasow...@redhat.com> > CC: Laszlo Ersek <ler...@redhat.com> > CC: Yuval Shaia <yuval.sh...@oracle.com> > CC: Palmer Dabbelt <pal...@sifive.com> > CC: Sagar Karandikar <sag...@eecs.berkeley.edu> > CC: Bastian Koppelmann <kbast...@mail.uni-paderborn.de> > CC: David Hildenbrand <da...@redhat.com> > CC: Thomas Huth <th...@redhat.com> > CC: Eric Farman <far...@linux.ibm.com> > CC: Matthew Rosato <mjros...@linux.ibm.com> > CC: Hannes Reinecke <h...@suse.com> > CC: Michael Walle <mich...@walle.cc> > CC: Artyom Tarasenko <atar4q...@gmail.com> > CC: Stefan Berger <stef...@linux.ibm.com> > CC: Samuel Thibault <samuel.thiba...@ens-lyon.org> > CC: Alex Williamson <alex.william...@redhat.com> > CC: Tony Krowiak <akrow...@linux.ibm.com> > CC: Pierre Morel <pmo...@linux.ibm.com> > CC: Michael Roth <mdr...@linux.vnet.ibm.com> > CC: Hailiang Zhang <zhang.zhanghaili...@huawei.com> > CC: Juan Quintela <quint...@redhat.com> > CC: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > CC: Luigi Rizzo <ri...@iet.unipi.it> > CC: Giuseppe Lettieri <g.letti...@iet.unipi.it> > CC: Vincenzo Maffione <v.maffi...@gmail.com> > CC: Jan Kiszka <jan.kis...@siemens.com> > CC: Anthony Green <gr...@moxielogic.com> > CC: Stafford Horne <sho...@gmail.com> > CC: Guan Xuetao <g...@mprc.pku.edu.cn> > CC: Max Filippov <jcmvb...@gmail.com> > CC: qemu-bl...@nongnu.org > CC: integrat...@gluster.org > CC: sheep...@lists.wpkg.org > CC: qemu-...@nongnu.org > CC: xen-de...@lists.xenproject.org > CC: qemu-...@nongnu.org > CC: qemu-s3...@nongnu.org > CC: qemu-ri...@nongnu.org > > include/qapi/error.h | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/include/qapi/error.h b/include/qapi/error.h > index d6898d833b..47238d9065 100644 > --- a/include/qapi/error.h > +++ b/include/qapi/error.h > @@ -345,6 +345,44 @@ 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_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 add 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. Missing: update of the big comment starting with "Error reporting system loosely patterned after Glib's GError."