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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 39096CA0EE8 for ; Wed, 17 Sep 2025 11:58:54 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uyqnt-00081k-6a; Wed, 17 Sep 2025 07:58:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uyqna-0007q4-LE for qemu-devel@nongnu.org; Wed, 17 Sep 2025 07:58:12 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uyqnX-00052h-CK for qemu-devel@nongnu.org; Wed, 17 Sep 2025 07:58:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758110285; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=GLbcYhOmZLOkQI2riqXN1sQU5QUildnLa02awuxxLvA=; b=Wc+VemoZm8DujJyN0e1pjtIgYpNY4gBcZDYETIrsyT+PvVrKbLU+JoanWiud4oieNnKBZL pu+EGrOK22tCtlGd/8e6pAqImkBHRqYjlucHJrl2pt7ACEoe2ZbsdBAgdLjnWXo+71+FKE FxgPdsIMcgEj794AJzvnfYydL+WDJMg= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-614-vfRmwMIKMIKOyYB0nkQjsQ-1; Wed, 17 Sep 2025 07:58:02 -0400 X-MC-Unique: vfRmwMIKMIKOyYB0nkQjsQ-1 X-Mimecast-MFC-AGG-ID: vfRmwMIKMIKOyYB0nkQjsQ_1758110277 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D6588195608B; Wed, 17 Sep 2025 11:57:54 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.195]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8976C19560B8; Wed, 17 Sep 2025 11:57:35 +0000 (UTC) Date: Wed, 17 Sep 2025 12:57:31 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Akihiko Odaki Cc: qemu-devel@nongnu.org, Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Paolo Bonzini , Eduardo Habkost , Peter Xu , David Hildenbrand , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Richard Henderson , Helge Deller , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , "Michael S. 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Iglesias" , xen-devel@lists.xenproject.org Subject: Re: [PATCH v3 0/7] Do not unparent in instance_finalize() Message-ID: References: <20250917-use-v3-0-72c2a6887c6c@rsg.ci.i.u-tokyo.ac.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250917-use-v3-0-72c2a6887c6c@rsg.ci.i.u-tokyo.ac.jp> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Sep 17, 2025 at 07:13:25PM +0900, Akihiko Odaki wrote: > Based-on: > ("[PATCH v2 00/14] hw/pci-host/raven clean ups") > > Supersedes: <20240829-memory-v1-1-ac07af2f4fa5@daynix.com> > ("[PATCH] docs/devel: Prohibit calling object_unparent() for memory region") > > Children are automatically unparented so manually unparenting is > unnecessary. Where is automatic unparenting you're referring to being done ? > Worse, automatic unparenting happens before the instance_finalize() > callback of the parent gets called, so object_unparent() calls in > the callback will refer to objects that are already unparented, which > is semantically incorrect. IIUC, object_property_add_child will acquire a reference on the child, and object_property_del_child (and thus object_unparent) will release that reference. The 'object_finalize' method, and thus 'instance_finalize' callback, won't be invoked until the last reference is dropped on the object in question. IOW, it should be impossible for 'object_finalize' to ever run, as long as the child has a parent set. So if we're in the 'finalize' then 'object_unparent' must be a no-op as the child must already have no references held and thus no parent. IOW, the reason to remove 'object_unparent' calls from finalize is surely because they do nothing at all, rather than this talk about callbacks being run at the wrong time ? > > Signed-off-by: Akihiko Odaki > --- > Changes in v3: > - Added patches to remove other object_unparent() calls in > instance_finalize(). > - Dropped patch "qdev: Automatically delete memory subregions" and the > succeeding patches to avoid Ccing many. > - Link to v2: https://lore.kernel.org/qemu-devel/20250915-use-v2-0-f4c7ff13bfe9@rsg.ci.i.u-tokyo.ac.jp > > Changes in v2: > - Added a reference to "[PATCH] docs/devel: Prohibit calling > object_unparent() for memory region", which does something similar to > patch "docs/devel: Do not unparent in instance_finalize()" but I > forgot I sent it in the past. > - Fixed a typo in patch > "docs/devel: Do not unparent in instance_finalize()" and > "[PATCH 02/22] vfio/pci: Do not unparent in instance_finalize()". > - Dropped patches to move address_space_init() calls; I intend to > QOM-ify to fix memory leaks automatically as discussed in the > following thread: > https://lore.kernel.org/qemu-devel/cd21698f-db77-eb75-6966-d559fdcab835@eik.bme.hu/ > But the QOM-ification will be big so I'll send it as a separate > series. > - Rebased on top of "[PATCH v2 00/14] hw/pci-host/raven clean ups". > https://lore.kernel.org/qemu-devel/cover.1751493467.git.balaton@eik.bme.hu/ > - Link to v1: https://lore.kernel.org/qemu-devel/20250906-use-v1-0-c51caafd1eb7@rsg.ci.i.u-tokyo.ac.jp > > --- > Akihiko Odaki (7): > docs/devel: Do not unparent in instance_finalize() > vfio/pci: Do not unparent in instance_finalize() > hw/core/register: Do not unparent in instance_finalize() > hv-balloon: hw/core/register: Do not unparent in instance_finalize() > hw/sd/sdhci: Do not unparent in instance_finalize() > vfio: Do not unparent in instance_finalize() > hw/xen: Do not unparent in instance_finalize() > > docs/devel/memory.rst | 19 ++++++------------- > hw/core/register.c | 1 - > hw/hyperv/hv-balloon.c | 12 +----------- > hw/sd/sdhci.c | 4 ---- > hw/vfio/pci-quirks.c | 9 +-------- > hw/vfio/pci.c | 4 ---- > hw/vfio/region.c | 3 --- > hw/xen/xen_pt_msi.c | 11 +---------- > 8 files changed, 9 insertions(+), 54 deletions(-) > --- > base-commit: e101d33792530093fa0b0a6e5f43e4d8cfe4581e > change-id: 20250906-use-37ecc903a9e0 > > Best regards, > -- > Akihiko Odaki > With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|