From: Greg Kurz <groug@kaod.org>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Cc: kwolf@redhat.com, Alberto Garcia <berto@igalia.com>,
pavel.dovgaluk@ispras.ru, qemu-block@nongnu.org,
qemu-devel@nongnu.org, armbru@redhat.com, stefanha@redhat.com,
pbonzini@redhat.com, mreitz@redhat.com, jsnow@redhat.com,
ari@tuxera.com
Subject: Re: [PATCH v2 12/13] block/qcow2: simplify qcow2_co_invalidate_cache()
Date: Fri, 18 Sep 2020 18:10:00 +0200 [thread overview]
Message-ID: <20200918181000.415d0016@bahia.lan> (raw)
In-Reply-To: <a009147d-bc03-9549-3d95-1b58ea830099@virtuozzo.com>
On Fri, 18 Sep 2020 19:01:34 +0300
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> wrote:
> 18.09.2020 18:51, Alberto Garcia wrote:
> > On Fri 18 Sep 2020 05:30:06 PM CEST, Greg Kurz wrote:
> >>> qcow2_do_open correctly sets errp on each failure path. So, we can
> >>> simplify code in qcow2_co_invalidate_cache() and drop explicit error
> >>> propagation. We should use ERRP_GUARD() (accordingly to comment in
> >>> include/qapi/error.h) together with error_append() call which we add to
> >>> avoid problems with error_fatal.
> >>>
> >>
> >> The wording gives the impression that we add error_append() to avoid problems
> >> with error_fatal which is certainly not true. Also it isn't _append() but
> >> _prepend() :)
> >>
> >> What about ?
> >>
> >> "Add ERRP_GUARD() as mandated by the documentation in include/qapi/error.h
> >> to avoid problems with the error_prepend() call if errp is
> >> &error_fatal."
>
> OK for me.
>
> >
> > I had to go to the individual error functions to see what "it doesn't
> > work with &error_fatal" actually means.
> >
> > So in a case like qcow2_do_open() which has:
> >
> > error_setg(errp, ...)
> > error_append_hint(errp, ...)
> >
> > As far as I can see this works just fine without ERRP_GUARD() and with
> > error_fatal, the difference is that if we don't use the guard then the
> > process exists during error_setg(), and if we use the guard it exists
> > during the implicit error_propagate() call triggered by its destruction
> > at the end of the function. In this latter case the printed error
> > message would include the hint.
> >
>
> Yes the only problem is that without ERRP_GUARD we lose the hint in case of error_fatal.
>
Yeah, so rather:
"Add ERRP_GUARD() as mandated by the documentation in include/qapi/error.h
so that error_prepend() is actually called even if errp is &error_fatal."
Cheers,
--
Greg
next prev parent reply other threads:[~2020-09-18 16:14 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-17 19:55 [PATCH v2 00/13] block: deal with errp: part I Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 01/13] block: return status from bdrv_append and friends Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 02/13] block: use return status of bdrv_append() Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 03/13] block: check return value of bdrv_open_child and drop error propagation Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 04/13] blockdev: fix drive_backup_prepare() missed error Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 05/13] block: drop extra error propagation for bdrv_set_backing_hd Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 06/13] block/mirror: drop extra error propagation in commit_active_start() Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 07/13] blockjob: return status from block_job_set_speed() Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 08/13] block/qcow2: qcow2_get_specific_info(): drop error propagation Vladimir Sementsov-Ogievskiy
2020-09-18 15:04 ` Alberto Garcia
2020-09-17 19:55 ` [PATCH v2 09/13] block/qcow2-bitmap: improve qcow2_load_dirty_bitmaps() interface Vladimir Sementsov-Ogievskiy
2020-09-18 14:54 ` Alberto Garcia
2020-09-18 14:59 ` Vladimir Sementsov-Ogievskiy
2020-09-18 15:15 ` Greg Kurz
2020-09-17 19:55 ` [PATCH v2 10/13] block/qcow2-bitmap: return status from qcow2_store_persistent_dirty_bitmaps Vladimir Sementsov-Ogievskiy
2020-09-18 15:21 ` Alberto Garcia
2020-09-17 19:55 ` [PATCH v2 11/13] block/qcow2: read_cache_sizes: return status value Vladimir Sementsov-Ogievskiy
2020-09-17 19:55 ` [PATCH v2 12/13] block/qcow2: simplify qcow2_co_invalidate_cache() Vladimir Sementsov-Ogievskiy
2020-09-18 15:26 ` Alberto Garcia
2020-09-18 15:30 ` Greg Kurz
2020-09-18 15:51 ` Alberto Garcia
2020-09-18 16:01 ` Vladimir Sementsov-Ogievskiy
2020-09-18 16:10 ` Greg Kurz [this message]
2020-09-17 19:55 ` [PATCH v2 13/13] block/qed: bdrv_qed_do_open: deal with errp Vladimir Sementsov-Ogievskiy
2020-09-18 16:07 ` Greg Kurz
2020-09-17 20:15 ` [PATCH v2 00/13] block: deal with errp: part I no-reply
2020-09-18 12:27 ` Vladimir Sementsov-Ogievskiy
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