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From: Greg Kurz <groug@kaod.org>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Cc: David Gibson <david@gibson.dropbear.id.au>,
	qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
	Markus Armbruster <armbru@redhat.com>
Subject: Re: [SPAM] Re: [PATCH 14/15] spapr: Simplify error handling in spapr_memory_plug()
Date: Tue, 15 Sep 2020 13:43:40 +0200	[thread overview]
Message-ID: <20200915134340.0cc3f9eb@bahia.lan> (raw)
In-Reply-To: <11f0dcb7-7923-0164-df69-4911b3293663@virtuozzo.com>

On Tue, 15 Sep 2020 13:58:53 +0300
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> wrote:

> 14.09.2020 15:35, Greg Kurz wrote:
> > As recommended in "qapi/error.h", add a bool return value to
> > spapr_add_lmbs() and spapr_add_nvdimm(), and use them instead
> > of local_err in spapr_memory_plug().
> > 
> > Since object_property_get_uint() only returns 0 on failure, use
> > that as well.
> 
> Why are you sure? Can't the property be 0 itself?
> 

Hmmm... I've based this assumption on the header:

 * Returns: the value of the property, converted to an unsigned integer, or 0
 * an error occurs (including when the property value is not an integer).

but looking at the implementation, I don't see any check that
a property cannot be 0 indeed...

It's a bit misleading to mention this in the header though. I
understand that the function should return something, which
should have a some explicitly assigned value to avoid compilers
or static analyzers to yell, but the written contract should be
that the value is _undefined_ IMHO.

In its present form, the only way to know if the property is
valid is to pass a non-NULL errp actually. I'd rather even see
that in the contract, and an assert() in the code.

An alternative would be to convert it to have a bool return
value and get the actual uint result with a pointer argument.

> > 
> > Also call ERRP_GUARD() to be able to check the status of void
> > function pc_dimm_plug() with *errp.
> > 
> 
> 

I'm now hesitating to either check *errp for object_property_get_uint()
too or simply drop this patch...


  reply	other threads:[~2020-09-15 11:44 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-14 12:34 [PATCH 00/15] spapr: Error handling fixes and cleanups (round 2) Greg Kurz
2020-09-14 12:34 ` [PATCH 01/15] spapr: Fix error leak in spapr_realize_vcpu() Greg Kurz
2020-09-15  9:08   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:00   ` Philippe Mathieu-Daudé
2020-09-14 12:34 ` [PATCH 02/15] ppc: Add a return value to ppc_set_compat() and ppc_set_compat_all() Greg Kurz
2020-09-15  9:18   ` Vladimir Sementsov-Ogievskiy
2020-09-15  9:34     ` Greg Kurz
2020-09-14 12:34 ` [PATCH 03/15] ppc: Fix return value in cpu_post_load() error path Greg Kurz
2020-09-15  9:50   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:01   ` Philippe Mathieu-Daudé
2020-09-14 12:34 ` [PATCH 04/15] spapr: Simplify error handling in callers of ppc_set_compat() Greg Kurz
2020-09-15  9:51   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:02   ` Philippe Mathieu-Daudé
2020-09-14 12:34 ` [PATCH 05/15] spapr: Get rid of cas_check_pvr() error reporting Greg Kurz
2020-09-15 10:03   ` Vladimir Sementsov-Ogievskiy
2020-09-15 11:00     ` [SPAM] " Greg Kurz
2020-09-14 12:34 ` [PATCH 06/15] spapr: Simplify error handling in do_client_architecture_support() Greg Kurz
2020-09-15 10:05   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:03   ` Philippe Mathieu-Daudé
2020-09-14 12:34 ` [PATCH 07/15] spapr: Simplify error handling in spapr_vio_busdev_realize() Greg Kurz
2020-09-15 10:15   ` Vladimir Sementsov-Ogievskiy
2020-09-14 12:34 ` [PATCH 08/15] spapr: Add a return value to spapr_drc_attach() Greg Kurz
2020-09-15 10:23   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:05   ` Philippe Mathieu-Daudé
2020-09-14 12:34 ` [PATCH 09/15] spapr: Simplify error handling in prop_get_fdt() Greg Kurz
2020-09-15 10:26   ` Vladimir Sementsov-Ogievskiy
2020-09-14 12:35 ` [PATCH 10/15] spapr: Add a return value to spapr_set_vcpu_id() Greg Kurz
2020-09-15 10:32   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:08   ` Philippe Mathieu-Daudé
2020-09-15 13:53     ` Greg Kurz
2020-09-17  1:06       ` David Gibson
2020-09-14 12:35 ` [PATCH 11/15] spapr: Simplify error handling in spapr_cpu_core_realize() Greg Kurz
2020-09-15 10:38   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:08   ` Philippe Mathieu-Daudé
2020-09-14 12:35 ` [PATCH 12/15] spapr: Add a return value to spapr_nvdimm_validate() Greg Kurz
2020-09-15 10:49   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:09   ` Philippe Mathieu-Daudé
2020-09-14 12:35 ` [PATCH 13/15] spapr: Add a return value to spapr_check_pagesize() Greg Kurz
2020-09-15 10:52   ` Vladimir Sementsov-Ogievskiy
2020-09-15 13:10   ` Philippe Mathieu-Daudé
2020-09-14 12:35 ` [PATCH 14/15] spapr: Simplify error handling in spapr_memory_plug() Greg Kurz
2020-09-15 10:58   ` Vladimir Sementsov-Ogievskiy
2020-09-15 11:43     ` Greg Kurz [this message]
2020-09-15 11:53       ` [SPAM] " Vladimir Sementsov-Ogievskiy
2020-09-15 12:04         ` Greg Kurz
2020-09-15 13:43           ` Greg Kurz
2020-09-17  1:15       ` [SPAM] " David Gibson
2020-09-17  7:38         ` Markus Armbruster
2020-09-17 10:04           ` Greg Kurz
2020-09-17 12:04             ` Markus Armbruster
2020-09-17 12:18               ` Daniel P. Berrangé
2020-09-17 12:40                 ` Greg Kurz
2020-09-17 13:17                 ` Markus Armbruster
2020-09-14 12:35 ` [PATCH 15/15] spapr: Simplify error handling in spapr_memory_unplug_request() Greg Kurz
2020-09-16  2:49 ` [PATCH 00/15] spapr: Error handling fixes and cleanups (round 2) David Gibson
2020-09-17  1:08   ` David Gibson

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