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GET /api/1.0/patches/2221296/?format=api
{ "id": 2221296, "url": "http://patchwork.ozlabs.org/api/1.0/patches/2221296/?format=api", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/1.0/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260409-work-qmp-monitor-hotplug-v4-3-89c4fdf69df1@kernel.org>", "date": "2026-04-09T07:18:20", "name": "[v4,3/5] qapi: add monitor-add, monitor-remove, query-monitors commands", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "a3b4d66dd581608150421d20df39bee9466427da", "submitter": { "id": 82326, "url": "http://patchwork.ozlabs.org/api/1.0/people/82326/?format=api", "name": "Christian Brauner", "email": "brauner@kernel.org" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260409-work-qmp-monitor-hotplug-v4-3-89c4fdf69df1@kernel.org/mbox/", "series": [ { "id": 499242, "url": "http://patchwork.ozlabs.org/api/1.0/series/499242/?format=api", "date": "2026-04-09T07:18:17", "name": "monitor: add dynamic QMP monitor hotplug support", "version": 4, "mbox": "http://patchwork.ozlabs.org/series/499242/mbox/" } ], "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2221296/checks/", "tags": {}, "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=R+I7mmn2;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)" ], "Received": [ "from lists.gnu.org (lists1p.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4frrtH1Dkfz211N\n\tfor <incoming@patchwork.ozlabs.org>; Thu, 09 Apr 2026 17:20:05 +1000 (AEST)", "from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from <qemu-devel-bounces@nongnu.org>)\n\tid 1wAjfJ-0007Mq-Qf; Thu, 09 Apr 2026 03:19:01 -0400", "from eggs.gnu.org ([2001:470:142:3::10])\n by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from <brauner@kernel.org>)\n id 1wAjfA-0007Lk-CP\n for qemu-devel@nongnu.org; Thu, 09 Apr 2026 03:18:52 -0400", "from tor.source.kernel.org ([172.105.4.254])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from <brauner@kernel.org>)\n id 1wAjf6-0000ZG-8M\n for qemu-devel@nongnu.org; Thu, 09 Apr 2026 03:18:51 -0400", "from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58])\n by tor.source.kernel.org (Postfix) with ESMTP id 79B4760125;\n Thu, 9 Apr 2026 07:18:40 +0000 (UTC)", "by smtp.kernel.org (Postfix) with ESMTPSA id 05F92C4CEF7;\n Thu, 9 Apr 2026 07:18:37 +0000 (UTC)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n s=k20201202; t=1775719120;\n bh=vfa+TrNtrxBo2wYtO9pePlx356JM3/1McvzEe45+0lQ=;\n h=From:Date:Subject:References:In-Reply-To:To:Cc:From;\n b=R+I7mmn2eGGTUwosgGWt6r6ZOVNsu2rSXUZfjCAk3GDGsF8UIP7uAJfnJ0QD4S0KR\n gF3CqwpNEMP49dFiPFNpfdHN5/9Tybg64S2u9SnIYkOSQLScFSOV+MofJZQLm44Tj1\n C/kTLWVTS/oSrRZysDZ88bELHl4jf3w8iucR5Xcn6OoQhSurPAtuXf9huzXx2gZjdH\n KZrD3M8+BoMul2zEOiFgG+Cb2tntKygu9TujWZZxzsCymYlzDONIEx7UcGUCeBlAn2\n mKS070yXoUUAupKvOjojrCaJdnVhiAEwcplvZhahugt35wu+XCts1QKjC+UhAZLS68\n R+U13ZDEjuFvg==", "From": "Christian Brauner <brauner@kernel.org>", "Date": "Thu, 09 Apr 2026 09:18:20 +0200", "Subject": "[PATCH v4 3/5] qapi: add monitor-add, monitor-remove,\n query-monitors commands", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "7bit", "Message-Id": "<20260409-work-qmp-monitor-hotplug-v4-3-89c4fdf69df1@kernel.org>", "References": "<20260409-work-qmp-monitor-hotplug-v4-0-89c4fdf69df1@kernel.org>", "In-Reply-To": "<20260409-work-qmp-monitor-hotplug-v4-0-89c4fdf69df1@kernel.org>", "To": "qemu-devel@nongnu.org", "Cc": "Markus Armbruster <armbru@redhat.com>, Eric Blake <eblake@redhat.com>,\n Fabiano Rosas <farosas@suse.de>, Laurent Vivier <lvivier@redhat.com>,\n Paolo Bonzini <pbonzini@redhat.com>, Thomas Huth <th.huth+qemu@posteo.eu>,\n\t=?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= <philmd@linaro.org>, =?utf-8?q?Dani?=\n\t=?utf-8?q?el_P=2E_Berrang=C3=A9?= <berrange@redhat.com>,\n Christian Brauner <brauner@kernel.org>", "X-Mailer": "b4 0.16-dev", "X-Developer-Signature": "v=1; a=openpgp-sha256; l=7958; i=brauner@kernel.org;\n h=from:subject:message-id; bh=vfa+TrNtrxBo2wYtO9pePlx356JM3/1McvzEe45+0lQ=;\n b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWReDzo6N1ry61WT19qz7A5qaSZy7atdpcUTcKVNak+Sx\n EOelb4rOkpZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACayT5aR4c1WjbpHno/lp3iz\n SzvPmJt3olRAu2n+jcn1kxe+UJY/WsHwi+m8RNo3/ufsO9ex/ymzLSqwc4g8Y3Oy6uqE9JyEuX7\n BjAA=", "X-Developer-Key": "i=brauner@kernel.org; a=openpgp;\n fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624", "Received-SPF": "pass client-ip=172.105.4.254; envelope-from=brauner@kernel.org;\n helo=tor.source.kernel.org", "X-Spam_score_int": "-25", "X-Spam_score": "-2.6", "X-Spam_bar": "--", "X-Spam_report": "(-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.54,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001,\n SPF_HELO_NONE=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 <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "Add QMP commands for monitor lifecycle management:\n\n- monitor-add: Create a QMP monitor on an existing chardev at runtime.\n The chardev must exist and not already have a frontend attached\n (enforced by qemu_chr_fe_init()). The new monitor starts in\n capability negotiation mode.\n\n- monitor-remove: Remove a QMP monitor. The removal sequence is:\n\n 1. Mark dead and remove from mon_list under monitor_lock. This\n must happen before disconnecting chardev handlers to prevent\n event broadcast from calling monitor_flush_locked() after the\n gcontext reset, which would create an out_watch on the wrong\n GMainContext (see monitor_cancel_out_watch()).\n 2. Cancel any pending out_watch while gcontext still points to the\n correct context.\n 3. Disconnect chardev handlers. For self-removal, preserve\n gcontext by passing the iothread GMainContext and keep the\n chardev connection open so the command response can be flushed.\n For normal removal, pass context=NULL and close the connection.\n 4. Drain pending requests from any in-flight monitor_qmp_read().\n 5. For self-removal, defer destruction to the dispatcher (the\n response must be flushed first). Otherwise destroy immediately\n via monitor_qmp_destroy().\n\n- query-monitors: Introspect all active monitors with their id, mode,\n and chardev name.\n\nThe motivating use case is systemd-vmspawn: when an external client\nrequests raw QMP access, vmspawn can create an independent QMP session\non demand rather than pre-allocating spare monitors at launch or\nbuilding an id-rewriting proxy.\n\nSigned-off-by: Christian Brauner (Amutable) <brauner@kernel.org>\n---\n monitor/qmp-cmds-control.c | 105 +++++++++++++++++++++++++++++++++++++++++++++\n qapi/control.json | 97 +++++++++++++++++++++++++++++++++++++++++\n 2 files changed, 202 insertions(+)", "diff": "diff --git a/monitor/qmp-cmds-control.c b/monitor/qmp-cmds-control.c\nindex 150ca9f5cb..33d02c8fb6 100644\n--- a/monitor/qmp-cmds-control.c\n+++ b/monitor/qmp-cmds-control.c\n@@ -219,3 +219,108 @@ SchemaInfoList *qmp_query_qmp_schema(Error **errp)\n }\n return schema;\n }\n+\n+void qmp_monitor_add(const char *id, const char *chardev,\n+ bool has_pretty, bool pretty, Error **errp)\n+{\n+ Chardev *chr;\n+\n+ /* Reject duplicate monitor id */\n+ if (monitor_find_by_id(id)) {\n+ error_setg(errp, \"monitor '%s' already exists\", id);\n+ return;\n+ }\n+\n+ chr = qemu_chr_find(chardev);\n+ if (!chr) {\n+ error_setg(errp, \"chardev '%s' not found\", chardev);\n+ return;\n+ }\n+\n+ monitor_init_qmp(chr, has_pretty && pretty, id, errp);\n+}\n+\n+void qmp_monitor_remove(const char *id, Error **errp)\n+{\n+ Monitor *mon;\n+ MonitorQMP *qmp_mon;\n+ bool self_remove;\n+\n+ mon = monitor_find_by_id(id);\n+ if (!mon) {\n+ error_setg(errp, \"monitor '%s' not found\", id);\n+ return;\n+ }\n+\n+ if (!mon->is_qmp) {\n+ error_setg(errp, \"monitor '%s' is not a QMP monitor\", id);\n+ return;\n+ }\n+\n+ qmp_mon = container_of(mon, MonitorQMP, common);\n+\n+ if (qatomic_read(&qmp_mon->setup_pending)) {\n+ error_setg(errp, \"monitor '%s' is still initializing\", id);\n+ return;\n+ }\n+\n+ self_remove = monitor_qmp_dispatcher_is_servicing(qmp_mon);\n+\n+ /* Remove from mon_list before chardev disconnect. */\n+ WITH_QEMU_LOCK_GUARD(&monitor_lock) {\n+ mon->dead = true;\n+ QTAILQ_REMOVE(&mon_list, mon, entry);\n+ }\n+\n+ /* Cancel out_watch while gcontext still points to the right ctx. */\n+ WITH_QEMU_LOCK_GUARD(&mon->mon_lock) {\n+ monitor_cancel_out_watch(mon);\n+ }\n+\n+ /*\n+ * Clear chardev handlers. Self-removal preserves gcontext so the\n+ * response flush creates out_watch on the correct GMainContext.\n+ */\n+ if (self_remove) {\n+ GMainContext *ctx = mon->use_io_thread\n+ ? iothread_get_g_main_context(mon_iothread) : NULL;\n+\n+ qemu_chr_fe_set_handlers(&mon->chr, NULL, NULL, NULL, NULL,\n+ NULL, ctx, false);\n+ } else {\n+ qemu_chr_fe_set_handlers(&mon->chr, NULL, NULL, NULL, NULL,\n+ NULL, NULL, true);\n+ }\n+\n+ /* Drain requests from any in-flight monitor_qmp_read(). */\n+ monitor_qmp_drain_queue(qmp_mon);\n+\n+ /* Self-removal: defer destruction so the response is flushed first. */\n+ if (self_remove) {\n+ return;\n+ }\n+\n+ monitor_qmp_destroy(qmp_mon);\n+ monitor_fdsets_cleanup();\n+}\n+\n+MonitorInfoList *qmp_query_monitors(Error **errp)\n+{\n+ MonitorInfoList *list = NULL;\n+ Monitor *mon;\n+\n+ WITH_QEMU_LOCK_GUARD(&monitor_lock) {\n+ QTAILQ_FOREACH(mon, &mon_list, entry) {\n+ MonitorInfo *info = g_new0(MonitorInfo, 1);\n+ Chardev *chr = qemu_chr_fe_get_driver(&mon->chr);\n+\n+ info->id = g_strdup(mon->id);\n+ info->mode = mon->is_qmp ? MONITOR_MODE_CONTROL\n+ : MONITOR_MODE_READLINE;\n+ info->chardev = g_strdup(chr ? chr->label : \"unknown\");\n+ QAPI_LIST_PREPEND(list, info);\n+ }\n+ }\n+\n+ return list;\n+}\ndiff --git a/qapi/control.json b/qapi/control.json\nindex 9a5302193d..eb4a30b59e 100644\n--- a/qapi/control.json\n+++ b/qapi/control.json\n@@ -211,3 +211,100 @@\n '*pretty': 'bool',\n 'chardev': 'str'\n } }\n+\n+##\n+# @monitor-add:\n+#\n+# Add a QMP monitor on an existing character device backend.\n+#\n+# The chardev must already exist (created via chardev-add or CLI).\n+# The monitor begins in capability negotiation mode -- the first\n+# client to connect receives the QMP greeting.\n+#\n+# @id: Monitor identifier, must be unique among monitors\n+#\n+# @chardev: Name of the character device backend to attach to\n+#\n+# @pretty: Enable pretty-printing of QMP responses (default: false)\n+#\n+# Errors:\n+# - If @id is already in use\n+# - If @chardev does not exist\n+#\n+# Since: 11.1\n+#\n+# .. qmp-example::\n+#\n+# -> { \"execute\": \"monitor-add\",\n+# \"arguments\": { \"id\": \"extra-qmp\",\n+# \"chardev\": \"qmp-extra\" } }\n+# <- { \"return\": {} }\n+##\n+{ 'command': 'monitor-add',\n+ 'data': { 'id': 'str',\n+ 'chardev': 'str',\n+ '*pretty': 'bool' } }\n+\n+##\n+# @monitor-remove:\n+#\n+# Remove a QMP monitor.\n+#\n+# The underlying chardev is NOT removed -- use chardev-remove\n+# separately if desired.\n+#\n+# If a client is currently connected, the connection is dropped.\n+#\n+# @id: Monitor identifier\n+#\n+# Errors:\n+# - If @id does not exist\n+# - If the monitor is not a QMP monitor\n+#\n+# Since: 11.1\n+#\n+# .. qmp-example::\n+#\n+# -> { \"execute\": \"monitor-remove\",\n+# \"arguments\": { \"id\": \"extra-qmp\" } }\n+# <- { \"return\": {} }\n+##\n+{ 'command': 'monitor-remove',\n+ 'data': { 'id': 'str' } }\n+\n+##\n+# @MonitorInfo:\n+#\n+# Information about a QMP/HMP monitor.\n+#\n+# @id: Monitor identifier. Always present for QMP monitors (auto-\n+# generated if not explicitly set). Absent for HMP monitors.\n+#\n+# @mode: Monitor mode (readline or control)\n+#\n+# @chardev: Name of the attached character device\n+#\n+# Since: 11.1\n+##\n+{ 'struct': 'MonitorInfo',\n+ 'data': { '*id': 'str',\n+ 'mode': 'MonitorMode',\n+ 'chardev': 'str' } }\n+\n+##\n+# @query-monitors:\n+#\n+# Return information about all active monitors.\n+#\n+# Returns: a list of @MonitorInfo for each active monitor\n+#\n+# Since: 11.1\n+#\n+# .. qmp-example::\n+#\n+# -> { \"execute\": \"query-monitors\" }\n+# <- { \"return\": [ { \"id\": \"mon0\", \"mode\": \"control\",\n+# \"chardev\": \"compat_monitor0\" } ] }\n+##\n+{ 'command': 'query-monitors',\n+ 'returns': ['MonitorInfo'] }\n", "prefixes": [ "v4", "3/5" ] }