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 D3F36C43458 for ; Fri, 3 Jul 2026 06:41:20 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wfXZv-0006BD-Ig; Fri, 03 Jul 2026 02:40:47 -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 1wfXZs-0006B5-Gl for qemu-devel@nongnu.org; Fri, 03 Jul 2026 02:40:44 -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 1wfXZn-0002os-Rj for qemu-devel@nongnu.org; Fri, 03 Jul 2026 02:40:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783060838; 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=Qf0BEzsEf9d8PbSUFTTOUgJBYMbr/fAnxhPbpHu84+w=; b=O/gpb0369C4f0/pg2tVkeT3elR6PhaYqgVKQJTUqEZ1oyTnGVF/65Bzo26hwv61xlKnYsf 4E0+D3u8l3/ZbVdLVvHUajIhwDyuKoYNvqjJAnWrbo9e7XAbamYwSeKMqJiPwkVw29HGrR wRsWVyT+uwv4CK6bdBVEzqkt61OXuik= 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-516-yKz4-DKUNUiUOSGtXcQ8QQ-1; Fri, 03 Jul 2026 02:40:33 -0400 X-MC-Unique: yKz4-DKUNUiUOSGtXcQ8QQ-1 X-Mimecast-MFC-AGG-ID: yKz4-DKUNUiUOSGtXcQ8QQ_1783060832 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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7DD4D187959E; Fri, 3 Jul 2026 06:40:31 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.4]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9C9DA1944DFC; Fri, 3 Jul 2026 06:40:30 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 2364A21E6920; Fri, 03 Jul 2026 08:40:28 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, Paolo Bonzini , "Dr. David Alan Gilbert" , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Alex =?utf-8?Q?Benn=C3=A9e?= , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Christian Brauner , devel@lists.libvirt.org Subject: Re: [PATCH v6 01/34] qom: replace 'can_be_deleted' with 'prepare_delete' In-Reply-To: <20260702160337.1910921-2-berrange@redhat.com> ("Daniel P. =?utf-8?Q?Berrang=C3=A9=22's?= message of "Thu, 2 Jul 2026 17:03:04 +0100") References: <20260702160337.1910921-1-berrange@redhat.com> <20260702160337.1910921-2-berrange@redhat.com> Date: Fri, 03 Jul 2026 08:40:28 +0200 Message-ID: <87mrw8y3s3.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 3.0 on 10.30.177.12 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. Old message: error_setg(errp, "object '%s' is in use, can not be deleted", id); New messages: error_setg(errp, "Cryptodev backend '%s' is still in use", error_setg(errp, "Host memory backend '%s' is still mapped", error_setg(errp, "IOMMUFD backend '%s' still has %d users", error_setg(errp, "Throttle group '%s' still has multiple references= ", error_setg(errp, "Deleting CAN bus device '%s' is not supported", error_setg(errp, "Deleting main loop '%s' is not supported", All now mention what kind of object it is. Users could probably figure this out from context easily. Welcome small improvement. The two unconditional ones become more accurate: they now report "not supported" instead of "in use". The other four lose "can not be deleted". Users can probably figure this out from context. Still, I lean towards error messages like "Can't DO-SOMETHING because REASON" until that becomes overly verbose. What do you think? > Signed-off-by: Daniel P. Berrang=C3=A9 [...] > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c > index 7080f85f95..ac992aa786 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(); No longer necessary. >=20=20 > - if (ucc->can_be_deleted) { > - return ucc->can_be_deleted(uc); > - } else { > - return true; > + 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)) { > return false; > } >=20=20 [...]