[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC v5 024/126] error: auto propagated local_err
On Fri, Oct 11, 2019 at 10:11 PM Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx> 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). > > 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.). > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx> > Reviewed-by: Eric Blake <eblake@xxxxxxxxxx> > --- > > CC: Gerd Hoffmann <kraxel@xxxxxxxxxx> > CC: "Gonglei (Arei)" <arei.gonglei@xxxxxxxxxx> > CC: Eduardo Habkost <ehabkost@xxxxxxxxxx> > CC: Igor Mammedov <imammedo@xxxxxxxxxx> > CC: Laurent Vivier <lvivier@xxxxxxxxxx> > CC: Amit Shah <amit@xxxxxxxxxx> > CC: Kevin Wolf <kwolf@xxxxxxxxxx> > CC: Max Reitz <mreitz@xxxxxxxxxx> > CC: John Snow <jsnow@xxxxxxxxxx> > CC: Ari Sundholm <ari@xxxxxxxxxx> > CC: Pavel Dovgalyuk <pavel.dovgaluk@xxxxxxxxx> > CC: Paolo Bonzini <pbonzini@xxxxxxxxxx> > CC: Stefan Hajnoczi <stefanha@xxxxxxxxxx> > CC: Fam Zheng <fam@xxxxxxxxxx> > CC: Stefan Weil <sw@xxxxxxxxxxx> > CC: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx> > CC: Peter Lieven <pl@xxxxxxx> > CC: Eric Blake <eblake@xxxxxxxxxx> > CC: "Denis V. Lunev" <den@xxxxxxxxxx> > CC: Markus Armbruster <armbru@xxxxxxxxxx> > CC: Alberto Garcia <berto@xxxxxxxxxx> > CC: Jason Dillaman <dillaman@xxxxxxxxxx> > CC: Wen Congyang <wencongyang2@xxxxxxxxxx> > CC: Xie Changlong <xiechanglong.d@xxxxxxxxx> > CC: Liu Yuan <namei.unix@xxxxxxxxx> > CC: "Richard W.M. Jones" <rjones@xxxxxxxxxx> > CC: Jeff Cody <codyprime@xxxxxxxxx> > CC: "Marc-André Lureau" <marcandre.lureau@xxxxxxxxxx> > CC: "Daniel P. Berrangé" <berrange@xxxxxxxxxx> > CC: Richard Henderson <rth@xxxxxxxxxxx> > CC: Greg Kurz <groug@xxxxxxxx> > CC: "Michael S. Tsirkin" <mst@xxxxxxxxxx> > CC: Marcel Apfelbaum <marcel.apfelbaum@xxxxxxxxx> > CC: Beniamino Galvani <b.galvani@xxxxxxxxx> > CC: Peter Maydell <peter.maydell@xxxxxxxxxx> > CC: "Cédric Le Goater" <clg@xxxxxxxx> > CC: Andrew Jeffery <andrew@xxxxxxxx> > CC: Joel Stanley <joel@xxxxxxxxx> > CC: Andrew Baumann <Andrew.Baumann@xxxxxxxxxxxxx> > CC: "Philippe Mathieu-Daudé" <philmd@xxxxxxxxxx> > CC: Antony Pavlov <antonynpavlov@xxxxxxxxx> > CC: Jean-Christophe Dubois <jcd@xxxxxxxxxxxxxxx> > CC: Peter Chubb <peter.chubb@xxxxxxxxxxxx> > CC: Subbaraya Sundeep <sundeep.lkml@xxxxxxxxx> > CC: Eric Auger <eric.auger@xxxxxxxxxx> > CC: Alistair Francis <alistair@xxxxxxxxxxxxx> > CC: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxx> > CC: Stefano Stabellini <sstabellini@xxxxxxxxxx> > CC: Anthony Perard <anthony.perard@xxxxxxxxxx> > CC: Paul Durrant <paul@xxxxxxx> > CC: Paul Burton <pburton@xxxxxxxxxxxx> > CC: Aleksandar Rikalo <arikalo@xxxxxxxxxxxx> > CC: Chris Wulff <crwulff@xxxxxxxxx> > CC: Marek Vasut <marex@xxxxxxx> > CC: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> > CC: Cornelia Huck <cohuck@xxxxxxxxxx> > CC: Halil Pasic <pasic@xxxxxxxxxxxxx> > CC: Christian Borntraeger <borntraeger@xxxxxxxxxx> > CC: "Hervé Poussineau" <hpoussin@xxxxxxxxxxx> > CC: Xiao Guangrong <xiaoguangrong.eric@xxxxxxxxx> > CC: Aurelien Jarno <aurelien@xxxxxxxxxxx> > CC: Aleksandar Markovic <amarkovic@xxxxxxxxxxxx> > CC: Mark Cave-Ayland <mark.cave-ayland@xxxxxxxxxxxx> > CC: Jason Wang <jasowang@xxxxxxxxxx> > CC: Laszlo Ersek <lersek@xxxxxxxxxx> > CC: Yuval Shaia <yuval.shaia@xxxxxxxxxx> > CC: Palmer Dabbelt <palmer@xxxxxxxxxx> > CC: Sagar Karandikar <sagark@xxxxxxxxxxxxxxxxx> > CC: Bastian Koppelmann <kbastian@xxxxxxxxxxxxxxxxxxxxx> > CC: David Hildenbrand <david@xxxxxxxxxx> > CC: Thomas Huth <thuth@xxxxxxxxxx> > CC: Eric Farman <farman@xxxxxxxxxxxxx> > CC: Matthew Rosato <mjrosato@xxxxxxxxxxxxx> > CC: Hannes Reinecke <hare@xxxxxxxx> > CC: Michael Walle <michael@xxxxxxxx> > CC: Artyom Tarasenko <atar4qemu@xxxxxxxxx> > CC: Stefan Berger <stefanb@xxxxxxxxxxxxx> > CC: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx> > CC: Alex Williamson <alex.williamson@xxxxxxxxxx> > CC: Tony Krowiak <akrowiak@xxxxxxxxxxxxx> > CC: Pierre Morel <pmorel@xxxxxxxxxxxxx> > CC: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx> > CC: Hailiang Zhang <zhang.zhanghailiang@xxxxxxxxxx> > CC: Juan Quintela <quintela@xxxxxxxxxx> > CC: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx> > CC: Luigi Rizzo <rizzo@xxxxxxxxxxxx> > CC: Giuseppe Lettieri <g.lettieri@xxxxxxxxxxxx> > CC: Vincenzo Maffione <v.maffione@xxxxxxxxx> > CC: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> > CC: Anthony Green <green@xxxxxxxxxxxxxx> > CC: Stafford Horne <shorne@xxxxxxxxx> > CC: Guan Xuetao <gxt@xxxxxxxxxxxxxxx> > CC: Max Filippov <jcmvbkbc@xxxxxxxxx> > CC: qemu-block@xxxxxxxxxx > CC: integration@xxxxxxxxxxx > CC: sheepdog@xxxxxxxxxxxxxx > CC: qemu-arm@xxxxxxxxxx > CC: xen-devel@xxxxxxxxxxxxxxxxxxxx > CC: qemu-ppc@xxxxxxxxxx > CC: qemu-s390x@xxxxxxxxxx > CC: qemu-riscv@xxxxxxxxxx > > 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). Nice improvements. Minor drawback, the abort()/exit() will now take place when going out of scope and running the cleanup instead of error location. Not a big problem I guess. > + * > + * 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. > -- > 2.21.0 > > Reviewed-by: Marc-André Lureau <marcandre.lureau@xxxxxxxxxx> -- Marc-André Lureau _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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