From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE5C4C432C3 for ; Mon, 18 Nov 2019 09:55:30 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A2A1C20692 for ; Mon, 18 Nov 2019 09:55:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2A1C20692 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60032 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iWdkn-0003rw-R7 for qemu-devel@archiver.kernel.org; Mon, 18 Nov 2019 04:55:29 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33049) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iWdgj-0001Kn-V9 for qemu-devel@nongnu.org; Mon, 18 Nov 2019 04:51:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iWdgi-0000xU-N6 for qemu-devel@nongnu.org; Mon, 18 Nov 2019 04:51:17 -0500 Received: from 4.mo179.mail-out.ovh.net ([46.105.36.149]:58542) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iWdgi-0000wn-Dy for qemu-devel@nongnu.org; Mon, 18 Nov 2019 04:51:16 -0500 Received: from player792.ha.ovh.net (unknown [10.108.35.131]) by mo179.mail-out.ovh.net (Postfix) with ESMTP id F41031435FB for ; Mon, 18 Nov 2019 10:51:13 +0100 (CET) Received: from kaod.org (lfbn-1-2229-223.w90-76.abo.wanadoo.fr [90.76.50.223]) (Authenticated sender: clg@kaod.org) by player792.ha.ovh.net (Postfix) with ESMTPSA id AFEFFC32D137; Mon, 18 Nov 2019 09:51:07 +0000 (UTC) Subject: Re: [PATCH v2 for-5.0 0/8] ppc: Consolidate QOM links and pointers to the same object To: Markus Armbruster , Greg Kurz References: <157383332103.165747.15204186097237659466.stgit@bahia.lan> <87zhgtwn63.fsf@dusky.pond.sub.org> From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= Message-ID: Date: Mon, 18 Nov 2019 10:51:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <87zhgtwn63.fsf@dusky.pond.sub.org> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Ovh-Tracer-Id: 7606861247232117521 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedufedrudeghedguddtucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdqfffguegfifdpvefjgfevmfevgfenuceurghilhhouhhtmecuhedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepuffvfhfhkffffgggjggtgfesthejredttdefheenucfhrhhomhepveorughrihgtpgfnvggpifhorghtvghruceotghlgheskhgrohgurdhorhhgqeenucfkpheptddrtddrtddrtddpledtrdejiedrhedtrddvvdefnecurfgrrhgrmhepmhhouggvpehsmhhtphdqohhuthdphhgvlhhopehplhgrhigvrhejledvrdhhrgdrohhvhhdrnhgvthdpihhnvghtpedtrddtrddtrddtpdhmrghilhhfrhhomheptghlgheskhgrohgurdhorhhgpdhrtghpthhtohepqhgvmhhuqdguvghvvghlsehnohhnghhnuhdrohhrghenucevlhhushhtvghrufhiiigvpedt X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 46.105.36.149 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: Peter Maydell , qemu-ppc@nongnu.org, qemu-devel@nongnu.org, David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 18/11/2019 10:26, Markus Armbruster wrote: > Greg Kurz writes: > >> There's a recurring pattern in the code where a const link is added to a >> newly instanciated object and the link is then used in the object's realize >> function to keep a pointer to the QOM entity which the link points to. >> >> void create_obj_b(Object *obj_a) >> { >> Object *obj_b; >> >> obj_b = object_new(TYPE_B); >> object_property_add_const_link(obj_b, "link-to-a", obj_a, &error_abort); >> object_property_set_bool(obj_b, true, "realized", &error_abort); >> } >> >> void object_b_realize(DeviceState *dev, Error **errp) >> { >> Object *obj_a; >> >> obj_a = object_property_get_link(OBJECT(dev), "link-to-a", errp); >> if (!obj_a) { >> return; >> } >> >> obj_b->obj_a = A(obj_a); // If obj_b->obj_a is changed, the link property >> // still points to the original obj_a that was >> // passed to object_property_add_const_link() >> } >> >> Confusing bugs could arise if the pointer and the link go out of sync for >> some reason. This can be avoided if the property is defined to directly use >> the pointer with the DEFINE_PROP_LINK() macro. >> >> This series just does that for all occurences of the fragile pattern in >> the XIVE and PNV code. > > Have you looked for the pattern elsewhere? I can take care of the Aspeed machine. I followed the same pattern there. C.