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 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B1CA0C4451B for ; Sat, 18 Jul 2026 21:38:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wlCio-00005P-1O; Sat, 18 Jul 2026 17:37:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wlCim-0008W4-1C; Sat, 18 Jul 2026 17:37:20 -0400 Received: from pdx-out-009.esa.us-west-2.outbound.mail-perimeter.amazon.com ([35.155.198.111]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wlCik-0001xW-0e; Sat, 18 Jul 2026 17:37:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1784410638; x=1815946638; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=IA4nALdfZQTZQBYqQKAyhaa+NqJeGaJYK8ZpoH8EEDo=; b=cUdm8OyehPTCxb839VlFO12Aq+7f7TRPQWsm6E8rvKt9vqD4XgqXVlHx U/95+VmG2c7rLhAZ+zggw+fmRZ475ftYFwkQf0uoNIJz79HHvrD3i8NTl JzFfViF4BBzQ7v7tSKjPRVtVgz5miIChILmF6jVPZZzchU1Al4sKiE2ja JbHTEQKs4pQLUd6KmUEz3VCYjy+/uZOwMAGbjQHgNWrWPYhWsITZMfr4m HXLX0bbO8CqjuEac1xz2iDY2wZd20HFAU4s3lk4HebZKNQ9xzBdE6wSGI tnX9zoWBdUBaq6OMrfaSwiR2MZ/0QPxrKd+m/dBq0Nfg0N5s/Uf7D6lOy Q==; X-CSE-ConnectionGUID: TIgUOO8ERKOQTOsykgQreg== X-CSE-MsgGUID: mLR7Sn1HREScAq49dTgluw== X-IronPort-AV: E=Sophos;i="6.25,171,1779148800"; d="scan'208";a="23816217" Received: from ip-10-5-0-115.us-west-2.compute.internal (HELO smtpout.naws.us-west-2.prod.farcaster.email.amazon.dev) ([10.5.0.115]) by internal-pdx-out-009.esa.us-west-2.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jul 2026 21:37:14 +0000 Received: from EX19MTAUWB002.ant.amazon.com [205.251.233.111:2580] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.58.199:2525] with esmtp (Farcaster) id 2d57d8dc-b67e-476f-8e56-f516b25e8f20; Sat, 18 Jul 2026 21:37:14 +0000 (UTC) X-Farcaster-Flow-ID: 2d57d8dc-b67e-476f-8e56-f516b25e8f20 Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWB002.ant.amazon.com (10.250.64.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.43; Sat, 18 Jul 2026 21:37:13 +0000 Received: from ip-10-253-83-51.amazon.com (172.19.99.218) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.43; Sat, 18 Jul 2026 21:37:04 +0000 From: Alexander Graf To: CC: , , , , Song Gao <17746591750@163.com>, Aditya Gupta , Alexey Kardashevskiy , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Farhan Ali , Alistair Francis , "Alistair Francis" , Antony Pavlov , Markus Armbruster , Artyom Tarasenko , BALATON Zoltan , Felipe Balbi , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Christian Borntraeger , Brian Cain , Hendrik Brueckner , Chao Liu , "Huacai Chen" , =?UTF-8?q?Cl=C3=A9ment=20Chigot?= , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= , Helge Deller , Dorjoy Chowdhury , "Edgar E . Iglesias" , Alexandre Iooss , Eric Farman , Fabiano Rosas , Francisco Iglesias , "Gaurav Sharma" , Gautam Gala , "Harsh Prateek Bora" , =?UTF-8?q?Herv=C3=A9=20Poussineau?= , Jan Kiszka , Max Filippov , Joel Stanley , Jared Rossi , Tyrone Ting , Frederic Konrad , Laurent Vivier , "Manos Pitsidianakis" , Bibo Mao , Mark Cave-Ayland , Glenn Miles , Matthew Rosato , Michael Rolnik , "Michael S . Tsirkin" , Niek Linnenbank , Nicholas Piggin , Palmer Dabbelt , Halil Pasic , Paolo Bonzini , Peter Maydell , Peter Xu , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , "Pierrick Bouvier" , Richard Henderson , Sai Pavan Boddu , Samuel Tardieu , Bernhard Beschow , Stafford Horne , Sergio Lopez , "Subbaraya Sundeep" , Thomas Huth , "Ran Wang" , Hao Wu Subject: [RFC PATCH v2 001/137] qom: Introduce object_new_child() Date: Sat, 18 Jul 2026 21:34:36 +0000 Message-ID: <20260718213652.37673-2-graf@amazon.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20260718213652.37673-1-graf@amazon.com> References: <20260711223707.42139-1-graf@amazon.com> <20260718213652.37673-1-graf@amazon.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [172.19.99.218] X-ClientProxiedBy: EX19D031UWA001.ant.amazon.com (10.13.139.88) To EX19D001UWA001.ant.amazon.com (10.13.138.214) Received-SPF: pass client-ip=35.155.198.111; envelope-from=prvs=65292d44c=graf@amazon.de; helo=pdx-out-009.esa.us-west-2.outbound.mail-perimeter.amazon.com X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, T_SPF_PERMERROR=0.01, UNPARSEABLE_RELAY=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org We already have two ways of creating a QOM object with a parent set from birth: object_initialize_child() for objects embedded in the parent struct, and object_new_with_props() for heap-allocated objects that also want a list of string properties applied. What we do not have is the plain heap-allocated dual of object_initialize_child(): create the object, add it as a child<> of a given parent under a given name, and hand the reference to the parent. Board and composite-device code that heap-allocates children today therefore either open-codes object_new()+object_property_add_child() +object_unref(), or skips the parenting step entirely and lets device_set_realized() dump the object into /machine/unattached. Add object_new_child(parent, id, typename) as that missing primitive. The reference created by object_new() is transferred to the parent's child<> property, so on return the sole reference is held by @parent and the caller does not need to unref. Later patches build the qdev and per-bus creation helpers on top of this. @id must be a valid QOM child<> property name: non-empty and without the "/" QOM path separator. It may contain the "[*]" auto-index suffix; the qdev id_wellformed() grammar does not apply here. The compiler enforces non-NULL arguments via __attribute__((nonnull)) instead of runtime asserts, as suggested by Richard and Peter. Link: https://lore.kernel.org/qemu-devel/87jyr3w9tc.fsf@pond.sub.org/ Suggested-by: Markus Armbruster Reviewed-by: Richard Henderson AI-used-for: code (refactoring) Signed-off-by: Alexander Graf --- include/qom/object.h | 32 ++++++++++++++++++++++++++++++++ qom/object.c | 12 ++++++++++++ 2 files changed, 44 insertions(+) diff --git a/include/qom/object.h b/include/qom/object.h index 11f55613fc..299673d040 100644 --- a/include/qom/object.h +++ b/include/qom/object.h @@ -632,6 +632,38 @@ Object *object_new_with_class(ObjectClass *klass); */ Object *object_new(const char *typename); +/** + * object_new_child: + * @parent: the QOM composition-tree parent + * @id: the child<> property name; the object's canonical QOM path + * becomes @parent's path plus "/" plus @id + * @typename: the name of the type of the object to instantiate + * + * Create a heap-allocated object and immediately add it to the QOM + * composition tree as a child of @parent. + * + * This is the heap-allocated dual of object_initialize_child(): use + * this when the child is a pointer member of the parent, and use + * object_initialize_child() when the child is embedded in the parent + * struct. See also object_new_with_props() for the variant that + * additionally sets a list of properties. + * + * The reference returned by object_new() is transferred to the child<> + * property of @parent, so the object has a reference count of 1 held + * by @parent, and the caller does not need to unref. + * + * The @id assert is a sanity check on the caller's string literal; + * the authoritative uniqueness check is object_property_add_child(), + * which will error_abort() on a duplicate @id under @parent. Use + * the "[*]" auto-index suffix when multiple children of the same + * kind may be created. + * + * Returns: the newly allocated, instantiated and parented object. + */ +Object *object_new_child(Object *parent, const char *id, + const char *typename) + __attribute__((nonnull(1, 2, 3), returns_nonnull)); + /** * object_new_with_props: * @typename: The name of the type of the object to instantiate. diff --git a/qom/object.c b/qom/object.c index f79b2cf361..64b0faf1f5 100644 --- a/qom/object.c +++ b/qom/object.c @@ -718,6 +718,18 @@ Object *object_new(const char *typename) return object_new_with_type(ti); } +Object *object_new_child(Object *parent, const char *id, + const char *typename) +{ + Object *obj; + + g_assert(id[0] && !strchr(id, '/')); + + obj = object_new(typename); + object_property_add_child(parent, id, obj); + object_unref(obj); + return obj; +} Object *object_new_with_props(const char *typename, Object *parent, -- 2.47.1