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 02125C43458 for ; Tue, 30 Jun 2026 07:35:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1weSzO-00065E-UN; Tue, 30 Jun 2026 03:34:38 -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 1weSzO-000656-3y for qemu-devel@nongnu.org; Tue, 30 Jun 2026 03:34:38 -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 1weSzM-00022D-C9 for qemu-devel@nongnu.org; Tue, 30 Jun 2026 03:34:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1782804874; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k1DK5bFzBDfi1rS2BlWOvTIVmqBmCpA0GW0zAYLoqpY=; b=HbayeddwgkKY0cJKOhGWF3MIf5KhUFC49ZR4LcSHVuJd2Iu4HIl6LGNfcqu2+kLQB1Mfly mR4raTMJcOX5ngBkDPxhEL0/hR3qgNUBHvkADen3026gKrWS+qHiiBgV68AObPwKOn37iY LT7kgo7KbqAL6MlUBaZeQJU9R4K5QW0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-662-9uO0v1xsNbGidrKhMzd0vw-1; Tue, 30 Jun 2026 03:34:32 -0400 X-MC-Unique: 9uO0v1xsNbGidrKhMzd0vw-1 X-Mimecast-MFC-AGG-ID: 9uO0v1xsNbGidrKhMzd0vw_1782804871 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 63EB41802669; Tue, 30 Jun 2026 07:34:30 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.4]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0B0731800667; Tue, 30 Jun 2026 07:34:28 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 7CF6821E6920; Tue, 30 Jun 2026 09:34:26 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, devel@lists.libvirt.org, =?utf-8?Q?Marc-Andr?= =?utf-8?Q?=C3=A9?= Lureau , Paolo Bonzini , "Dr. David Alan Gilbert" , Alex =?utf-8?Q?Benn=C3=A9e?= , Christian Brauner , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Peter Krempa Subject: Re: [PATCH v5 01/35] qom: replace 'can_be_deleted' with 'prepare_delete' In-Reply-To: <20260624173752.2928717-2-berrange@redhat.com> ("Daniel P. =?utf-8?Q?Berrang=C3=A9=22's?= message of "Wed, 24 Jun 2026 18:37:17 +0100") References: <20260624173752.2928717-1-berrange@redhat.com> <20260624173752.2928717-2-berrange@redhat.com> Date: Tue, 30 Jun 2026 09:34:26 +0200 Message-ID: <87qzlopjlp.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-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 Daniel P. Berrang=C3=A9 writes: > While most objects can perform all their cleanup in the finalizer > method, there can be interactions with other resources / subsystems > / threads which require that some cleanup be performed on an user > creatable object before unparenting it and entering finalization. > > The current 'can_be_deleted' method runs in the deletion path and > is intended to be used to block deletion. While it could be used > to perform cleanup tasks, its name suggests it should be free of > side-effects. > > Generalize this by renaming it to 'prepare_delete', explicitly > allowing for cleanup to be provided. Existing users of 'can_be_deleted' > are re-written, which provides them with more detailed/tailored error > messages. > > Reviewed-by: Marc-Andr=C3=A9 Lureau > Tested-by: Peter Krempa > Signed-off-by: Daniel P. Berrang=C3=A9 [...] > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c > index 7080f85f95..6faa0b2fd9 100644 > --- a/qom/object_interfaces.c > +++ b/qom/object_interfaces.c > @@ -32,16 +32,15 @@ bool user_creatable_complete(UserCreatable *uc, Error= **errp) > return !*errp; > } >=20=20 > -bool user_creatable_can_be_deleted(UserCreatable *uc) > +bool user_creatable_prepare_delete(UserCreatable *uc, Error **errp) > { > - > UserCreatableClass *ucc =3D USER_CREATABLE_GET_CLASS(uc); > + ERRP_GUARD(); >=20=20 > - if (ucc->can_be_deleted) { > - return ucc->can_be_deleted(uc); > - } else { > - return true; > + if (ucc->prepare_delete) { > + ucc->prepare_delete(uc, errp); > } > + return !*errp; > } Simpler: if (ucc->prepare_delete) { return ucc->prepare_delete(uc, errp); } return true; >=20=20 > void user_creatable_add_qapi(ObjectOptions *options, Error **errp) > @@ -253,8 +252,7 @@ bool user_creatable_del(const char *id, Error **errp) > return false; > } >=20=20 > - if (!user_creatable_can_be_deleted(USER_CREATABLE(obj))) { > - error_setg(errp, "object '%s' is in use, can not be deleted", id= ); > + if (!user_creatable_prepare_delete(USER_CREATABLE(obj), errp)) { This changes error messages. The old ones mention @id. The new ones don't: error_setg(errp, "Cryptodev backend is still in use"); error_setg(errp, "Host memory backend is still mapped"); error_setg(errp, "IOMMUFD backend still has %d users", be->users); error_setg(errp, "Throttle group still has multiple references"); error_setg(errp, "Deleting can bus devices is not supported"); error_setg(errp, "Deleting main loop is not supported"); Visible in the diff to tests/qemu-iotests/245 below. Because this runs within object-del, and @id is the argument provided by the user there, the error message is still sufficiently clear, I guess. If this ever gets used where the object isn't obvious to the user from context, the error messages become sub-par. Observation, not a demand. Please cover this change in the commit message. > return false; > } >=20=20 > diff --git a/tests/qemu-iotests/245 b/tests/qemu-iotests/245 > index f96610f510..e161bcfda9 100755 > --- a/tests/qemu-iotests/245 > +++ b/tests/qemu-iotests/245 > @@ -801,7 +801,7 @@ class TestBlockdevReopen(iotests.QMPTestCase): > # Now group1 is in use, it cannot be deleted > result =3D self.vm.qmp('object-del', id =3D 'group1') > self.assert_qmp(result, 'error/class', 'GenericError') > - self.assert_qmp(result, 'error/desc', "object 'group1' is in use= , can not be deleted") > + self.assert_qmp(result, 'error/desc', "Throttle group still has = multiple references") >=20=20 > # Default options, this switches the group back to group0 > self.reopen(opts) > @@ -809,7 +809,7 @@ class TestBlockdevReopen(iotests.QMPTestCase): > # So now we cannot delete group0 > result =3D self.vm.qmp('object-del', id =3D 'group0') > self.assert_qmp(result, 'error/class', 'GenericError') > - self.assert_qmp(result, 'error/desc', "object 'group0' is in use= , can not be deleted") > + self.assert_qmp(result, 'error/desc', "Throttle group still has = multiple references") >=20=20 > # But group1 is free this time, and it can be deleted > self.vm.cmd('object-del', id =3D 'group1') > diff --git a/util/main-loop.c b/util/main-loop.c > index ad8645c30a..67ee06c311 100644 > --- a/util/main-loop.c > +++ b/util/main-loop.c > @@ -218,8 +218,9 @@ static void main_loop_init(EventLoopBase *base, Error= **errp) > mloop =3D m; > } >=20=20 > -static bool main_loop_can_be_deleted(EventLoopBase *base) > +static bool main_loop_prepare_delete(EventLoopBase *base, Error **errp) > { > + error_setg(errp, "Deleting main loop is not supported"); > return false; > } >=20=20 > @@ -229,7 +230,7 @@ static void main_loop_class_init(ObjectClass *oc, con= st void *class_data) >=20=20 > bc->init =3D main_loop_init; > bc->update_params =3D main_loop_update_params; > - bc->can_be_deleted =3D main_loop_can_be_deleted; > + bc->prepare_delete =3D main_loop_prepare_delete; > } >=20=20 > static const TypeInfo main_loop_info =3D {