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 67781CD98ED for ; Thu, 18 Jun 2026 11:03:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1waAU8-0000TP-2n; Thu, 18 Jun 2026 07:00:36 -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 1waAU3-0000FA-3h for qemu-devel@nongnu.org; Thu, 18 Jun 2026 07:00:33 -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 1waAU1-00035U-1S for qemu-devel@nongnu.org; Thu, 18 Jun 2026 07:00:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1781780428; 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=+DiqiuAoyzpcmTmO1qDIbEjH8n0qU8CDdYBQcQOhM50=; b=Xqzq8HJsUbsG7DIlF+MPKVEeYN9/ZOOL4w+3lR7Beh4/NMH9Roh1+FGkYIuRylOrI32+ay 5IwFwVv/pKKu1UtBxk9u6nyCN+lax638xR+hVl947t6SW5CxZSGDwlUeQelDPAWF0IYgjh lM3tdGZtwSf94PG5xYVddAz3qyrFw04= 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-509-cZLHG-DBMsKJYToQ-rEMjw-1; Thu, 18 Jun 2026 07:00:24 -0400 X-MC-Unique: cZLHG-DBMsKJYToQ-rEMjw-1 X-Mimecast-MFC-AGG-ID: cZLHG-DBMsKJYToQ-rEMjw_1781780423 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E2BA8180058F; Thu, 18 Jun 2026 11:00:22 +0000 (UTC) Received: from berrange.com (unknown [10.44.49.28]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id CCB5F1956087; Thu, 18 Jun 2026 11:00:19 +0000 (UTC) From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: devel@lists.libvirt.org, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Christian Brauner , Markus Armbruster , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , "Dr. David Alan Gilbert" , Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PATCH v3 26/35] monitor: implement support for deleting QMP objects Date: Thu, 18 Jun 2026 11:58:27 +0100 Message-ID: <20260618105836.991609-27-berrange@redhat.com> In-Reply-To: <20260618105836.991609-1-berrange@redhat.com> References: <20260618105836.991609-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@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 From: Christian Brauner The removal sequence is: 1. Remove from mon_list under monitor_lock. This must happen before disconnecting chardev handlers to prevent event broadcast from calling monitor_flush_locked() after the gcontext reset, which would create an out_watch on the wrong GMainContext (see monitor_cancel_out_watch()). 2. Cancel any pending out_watch while gcontext still points to the correct context. 3. Disconnect chardev handlers, passing context=NULL and close the connection. 4. Drain pending requests from any in-flight monitor_qmp_read(). 5. Destroy the monitor object Signed-off-by: Christian Brauner (Amutable) [DB: extracted from a larger commit and refactored to apply to the new monitor class structure. Remove 'self delete' feature which requires complex special-case code] Signed-off-by: Daniel P. Berrangé --- monitor/monitor-internal.h | 2 ++ monitor/monitor.c | 22 ++++++++++++++++ monitor/qmp.c | 54 ++++++++++++++++++++++++++++++++++++-- 3 files changed, 76 insertions(+), 2 deletions(-) diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h index a82e1aacb6..5522e05464 100644 --- a/monitor/monitor-internal.h +++ b/monitor/monitor-internal.h @@ -178,6 +178,7 @@ struct MonitorQMP { Monitor parent_obj; JSONMessageParser parser; bool pretty; + bool setup_pending; /* iothread BH has not yet set up chardev handlers */ /* * When a client connects, we're in capabilities negotiation mode. * @commands is &qmp_cap_negotiation_commands then. When command @@ -206,6 +207,7 @@ extern MonitorList mon_list; bool monitor_requires_iothread(const Monitor *mon); int monitor_can_read(void *opaque); +void monitor_cancel_out_watch(Monitor *mon); void monitor_list_append(Monitor *mon); void monitor_fdsets_cleanup(void); int monitor_set_cpu(Monitor *mon, int cpu_index); diff --git a/monitor/monitor.c b/monitor/monitor.c index 0e1c623555..b155f58546 100644 --- a/monitor/monitor.c +++ b/monitor/monitor.c @@ -177,6 +177,28 @@ static gboolean monitor_unblocked(void *do_not_use, GIOCondition cond, return G_SOURCE_REMOVE; } +/* Cancel a pending out_watch GSource. Caller must hold mon_lock. */ +void monitor_cancel_out_watch(Monitor *mon) +{ + if (mon->out_watch) { + GMainContext *ctx = NULL; + GSource *src; + + if (monitor_requires_iothread(mon)) { + ctx = iothread_get_g_main_context(mon_iothread); + } + src = g_main_context_find_source_by_id(ctx, mon->out_watch); + if (!src && ctx) { + /* Handler disconnect may have reset gcontext to NULL. */ + src = g_main_context_find_source_by_id(NULL, mon->out_watch); + } + if (src) { + g_source_destroy(src); + } + mon->out_watch = 0; + } +} + /* Caller must hold mon->mon_lock */ void monitor_flush_locked(Monitor *mon) { diff --git a/monitor/qmp.c b/monitor/qmp.c index 2131be82c7..5301927f09 100644 --- a/monitor/qmp.c +++ b/monitor/qmp.c @@ -184,6 +184,12 @@ static void monitor_qmp_cleanup_req_queue_locked(MonitorQMP *mon) } } +static void monitor_qmp_drain_queue(MonitorQMP *mon) +{ + QEMU_LOCK_GUARD(&mon->qmp_queue_lock); + monitor_qmp_cleanup_req_queue_locked(mon); +} + static void monitor_qmp_cleanup_queue_and_resume(MonitorQMP *mon) { QEMU_LOCK_GUARD(&mon->qmp_queue_lock); @@ -597,6 +603,7 @@ static void monitor_qmp_setup_handlers_bh(void *opaque) monitor_qmp_read, monitor_qmp_event, NULL, &mon->parent_obj, context, true); monitor_list_append(&mon->parent_obj); + qatomic_set(&mon->setup_pending, false); } void monitor_new_qmp(const char *chardev_id, bool pretty, Error **errp) @@ -645,6 +652,7 @@ static void monitor_qmp_complete(UserCreatable *uc, Error **errp) * since chardev might be running in the monitor I/O * thread. Schedule a bottom half. */ + mon->setup_pending = true; aio_bh_schedule_oneshot(iothread_get_aio_context(mon_iothread), monitor_qmp_setup_handlers_bh, mon); /* The bottom half will add @mon to @mon_list */ @@ -656,8 +664,14 @@ static void monitor_qmp_complete(UserCreatable *uc, Error **errp) } } +static void monitor_qmp_iothread_quiesce(void *opaque) +{ + /* No-op: synchronization point only */ +} + static bool monitor_qmp_prepare_delete(UserCreatable *uc, Error **errp) { + Monitor *mon = MONITOR(uc); MonitorQMP *qmp = MONITOR_QMP(uc); if (monitor_qmp_dispatcher_is_servicing(qmp)) { @@ -665,8 +679,44 @@ static bool monitor_qmp_prepare_delete(UserCreatable *uc, Error **errp) return false; } - error_setg(errp, "Deleting QMP monitors is not supported"); - return false; + if (qatomic_read(&qmp->setup_pending)) { + error_setg(errp, "monitor is still initializing"); + return false; + } + + /* Remove from mon_list before chardev disconnect. */ + WITH_QEMU_LOCK_GUARD(&monitor_lock) { + QTAILQ_REMOVE(&mon_list, mon, entry); + } + + /* Cancel out_watch while gcontext still points to the right ctx. */ + WITH_QEMU_LOCK_GUARD(&mon->mon_lock) { + monitor_cancel_out_watch(mon); + } + + qemu_chr_fe_set_handlers(&mon->chr, NULL, NULL, NULL, NULL, + NULL, NULL, true); + + /* Drain requests from any in-flight monitor_qmp_read(). */ + monitor_qmp_drain_queue(qmp); + + WITH_QEMU_LOCK_GUARD(&mon->mon_lock) { + /* Disable flushes before cancel -- gcontext is already wrong. */ + qemu_chr_fe_set_open(&mon->chr, false); + monitor_cancel_out_watch(mon); + } + + /* Synchronize with in-flight iothread callbacks. */ + if (monitor_requires_iothread(mon)) { + aio_wait_bh_oneshot(iothread_get_aio_context(mon_iothread), + monitor_qmp_iothread_quiesce, NULL); + } + + /* Catch requests from a racing monitor_qmp_read(). */ + monitor_qmp_drain_queue(qmp); + monitor_fdsets_cleanup(); + + return true; } static void monitor_qmp_accept_input(Monitor *mon) -- 2.54.0