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 020B0C43458 for ; Thu, 2 Jul 2026 14:08:07 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wfI56-0000ah-Uh; Thu, 02 Jul 2026 10:07:56 -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 1wfI51-0000aJ-Aa for qemu-devel@nongnu.org; Thu, 02 Jul 2026 10:07:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wfI4y-0005Du-NH for qemu-devel@nongnu.org; Thu, 02 Jul 2026 10:07:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783001266; 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=i3RDCN2vN7VaEcfPzoYZ0jodyZY2aWslYWNMdSBdpHo=; b=fYC3aSew8ghQz61S6JXiTGczAmMazU7QWScUOr607IXUaHN5MPnN0fMesCwx15jI6ylKF2 rwKe7Cyvr1dI4f9cauBEXM0ICHKvbjD8/x+PjkjXOqbNdR2rXq4cPHFRCVRtyBoPIsB8T9 INFhYZEHSwkgnjg4oE4O78qvAMcX5fQ= Received: from mx-prod-mc-06.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-149-I7ri7vt8Mbqh5vPueTaHEQ-1; Thu, 02 Jul 2026 10:07:43 -0400 X-MC-Unique: I7ri7vt8Mbqh5vPueTaHEQ-1 X-Mimecast-MFC-AGG-ID: I7ri7vt8Mbqh5vPueTaHEQ_1783001262 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B81C21833388; Thu, 2 Jul 2026 14:07:41 +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 A57CA1800841; Thu, 2 Jul 2026 14:07:40 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3B4EE21E6920; Thu, 02 Jul 2026 16:07:38 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: marcandre.lureau@redhat.com, qemu-devel@nongnu.org, devel@lists.libvirt.org, 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 32/35] monitor: add support for auto-deleting monitors upon close In-Reply-To: ("Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9=22's?= message of "Thu, 2 Jul 2026 14:32:33 +0100") References: <20260624173752.2928717-1-berrange@redhat.com> <20260624173752.2928717-33-berrange@redhat.com> <178233405051.3955748.10990724544083287885.b4-review@b4> <87zf0busnt.fsf@pond.sub.org> Date: Thu, 02 Jul 2026 16:07:38 +0200 Message-ID: <877bndzdqt.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=170.10.129.124; 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_H3=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: > On Wed, Jul 01, 2026 at 08:32:06AM +0200, Markus Armbruster wrote: [...] >> >> static void monitor_qmp_event(void *opaque, QEMUChrEvent event) >> >> { >> >> QDict *data; >> >> MonitorQMP *mon =3D opaque; >> >>=20=20 >> >> + /* Protect against race if a client drops & quickly >> >> + * reconnects - we'll have the delete BH scheduled >> >> + * so must not honour a new open request >> >> + */ >> >> + if (mon->delete_pending) { >> >> + return; >> >> + } >>=20 >> Consider "something happens between setting @delete_pending and monitor >> destruction that triggers the event" and "same thing happens after >> destruction". Any observable differences in behavior? >>=20 >> Are there any other monitor interactions that might need similar >> special-casing when @delete_pending? > > When the BH deletes the monitor object, it will disconnect the > chardev handlers. So there is no possibility of monitor_qmp_event > being called after the monitor QOM destruction is complete. The > only race is between this method and the start of the BH. Add this completeness argument to the commit message?