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GET /api/1.0/patches/2219333/?format=api
{ "id": 2219333, "url": "http://patchwork.ozlabs.org/api/1.0/patches/2219333/?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": "<20260402-work-qmp-monitor-hotplug-v1-2-6313a5cdd574@kernel.org>", "date": "2026-04-02T21:19:17", "name": "[2/5] monitor/qmp: add infrastructure for safe dynamic monitor removal", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "fc22dfd9e8a8304735c523e4a66444bc0fb069d5", "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/20260402-work-qmp-monitor-hotplug-v1-2-6313a5cdd574@kernel.org/mbox/", "series": [ { "id": 498554, "url": "http://patchwork.ozlabs.org/api/1.0/series/498554/?format=api", "date": "2026-04-02T21:19:15", "name": "monitor: add dynamic QMP monitor hotplug support", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/498554/mbox/" } ], "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2219333/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=dgAYVc21;\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 (lists.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 4fmvsZ0H7vz1yCs\n\tfor <incoming@patchwork.ozlabs.org>; Fri, 03 Apr 2026 08:20:50 +1100 (AEDT)", "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 1w8PS6-0003kI-2m; Thu, 02 Apr 2026 17:19:46 -0400", "from eggs.gnu.org ([2001:470:142:3::10])\n by lists.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 1w8PS5-0003k9-6P\n for qemu-devel@nongnu.org; Thu, 02 Apr 2026 17:19:45 -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 1w8PS3-0004au-Jz\n for qemu-devel@nongnu.org; Thu, 02 Apr 2026 17:19:44 -0400", "from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58])\n by tor.source.kernel.org (Postfix) with ESMTP id A6ABB60123;\n Thu, 2 Apr 2026 21:19:35 +0000 (UTC)", "by smtp.kernel.org (Postfix) with ESMTPSA id 3E04DC116C6;\n Thu, 2 Apr 2026 21:19:33 +0000 (UTC)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n s=k20201202; t=1775164775;\n bh=bSL21DMJvdPmisuJ4sR+uubo6LsKzZepTDyv0CmheLU=;\n h=From:Date:Subject:References:In-Reply-To:To:Cc:From;\n b=dgAYVc21yM/2Vjc90j9dbQAcYoc1fLCXqQkzFCt296qDhe2Go0aqs8USaGnebPNio\n ynpNo/A7T9a7UCDM631goZ8SsOzdpIaMKYQX1ErQbSbfG/ExO8qx45NqA2m+gqluwU\n V/PbZAtnNluv/ZWQGVeO0CBrQkoABToqBhvY1qfgXhiOKpoiwilUcLqJZ/lYAzhVVE\n D2Ea7z9M+rDtOBrJngc8Vj9N9tsnoZDe2Vx8kRupZzQ8vrqhdvMJQS9AkglcGvYWuh\n crh7pCL48m58VQB7JXVlRn54cKyWrVaH6BXGYLxKQWNZ89CsAezoQ2d8Cblh5AtwkO\n guTavDLZHgn9A==", "From": "Christian Brauner <brauner@kernel.org>", "Date": "Thu, 02 Apr 2026 23:19:17 +0200", "Subject": "[PATCH 2/5] monitor/qmp: add infrastructure for safe dynamic\n monitor removal", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "7bit", "Message-Id": "<20260402-work-qmp-monitor-hotplug-v1-2-6313a5cdd574@kernel.org>", "References": "<20260402-work-qmp-monitor-hotplug-v1-0-6313a5cdd574@kernel.org>", "In-Reply-To": "<20260402-work-qmp-monitor-hotplug-v1-0-6313a5cdd574@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=4106; i=brauner@kernel.org;\n h=from:subject:message-id; bh=bSL21DMJvdPmisuJ4sR+uubo6LsKzZepTDyv0CmheLU=;\n b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSeuxv/foer4afmkxfEPMt39E6PC9TgvHlBZ07SqQKXN\n a7dR9+ndJSyMIhxMciKKbI4tJuEyy3nqdhslKkBM4eVCWQIAxenAEyk/hYjw2G3CWZtnW2CX7LM\n vapdfY1U3x/pD4t3eBmSUHDn67XPtQz/LHwzfi7IfaqYtNZi1Yl3WkKnl0rcP+jTvmj+tmzNNYV\n ZXAA=", "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=-0.542,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001,\n RCVD_IN_VALIDITY_RPBL_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": "Extract monitor_qmp_destroy() from the shutdown-time monitor_cleanup()\npath to allow destroying a single QMP monitor at runtime without\nshutting down the entire dispatcher coroutine.\n\nExport monitor_qmp_cleanup_queue_and_resume() so that monitor-remove\ncan drain pending requests before destroying the monitor.\n\nAdd qmp_dispatcher_current_mon tracking in the dispatcher coroutine to\nhandle the case where a monitor sends monitor-remove targeting itself.\nAfter dispatching each request, the dispatcher checks the dead flag: if\nset, it calls monitor_qmp_destroy() and clears the tracking pointer.\n\nBoth the dispatcher yield points and QMP command handlers run under the\nBQL, so no additional locking is needed for qmp_dispatcher_current_mon.\n\nSigned-off-by: Christian Brauner (Amutable) <brauner@kernel.org>\n---\n monitor/monitor-internal.h | 3 +++\n monitor/qmp.c | 36 +++++++++++++++++++++++++++++++++++-\n 2 files changed, 38 insertions(+), 1 deletion(-)", "diff": "diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h\nindex 8f5fe7c111..40f76ef5a0 100644\n--- a/monitor/monitor-internal.h\n+++ b/monitor/monitor-internal.h\n@@ -181,10 +181,13 @@ void monitor_fdsets_cleanup(void);\n \n void qmp_send_response(MonitorQMP *mon, const QDict *rsp);\n void monitor_data_destroy_qmp(MonitorQMP *mon);\n+void monitor_qmp_destroy(MonitorQMP *mon);\n+void monitor_qmp_cleanup_queue_and_resume(MonitorQMP *mon);\n void coroutine_fn monitor_qmp_dispatcher_co(void *data);\n void qmp_dispatcher_co_wake(void);\n \n Monitor *monitor_find_by_id(const char *id);\n+bool monitor_qmp_dispatcher_is_servicing(MonitorQMP *mon);\n \n int get_monitor_def(Monitor *mon, int64_t *pval, const char *name);\n void handle_hmp_command(MonitorHMP *mon, const char *cmdline);\ndiff --git a/monitor/qmp.c b/monitor/qmp.c\nindex 5fbc7af074..0d393f3c96 100644\n--- a/monitor/qmp.c\n+++ b/monitor/qmp.c\n@@ -71,6 +71,13 @@ typedef struct QMPRequest QMPRequest;\n \n QmpCommandList qmp_commands, qmp_cap_negotiation_commands;\n \n+/*\n+ * The monitor currently being serviced by the dispatcher coroutine.\n+ * Both the dispatcher and QMP command handlers (monitor-remove) run\n+ * under the BQL, so no additional locking is needed.\n+ */\n+static MonitorQMP *qmp_dispatcher_current_mon;\n+\n static bool qmp_oob_enabled(MonitorQMP *mon)\n {\n return mon->capab[QMP_CAPABILITY_OOB];\n@@ -98,7 +105,7 @@ static void monitor_qmp_cleanup_req_queue_locked(MonitorQMP *mon)\n }\n }\n \n-static void monitor_qmp_cleanup_queue_and_resume(MonitorQMP *mon)\n+void monitor_qmp_cleanup_queue_and_resume(MonitorQMP *mon)\n {\n QEMU_LOCK_GUARD(&mon->qmp_queue_lock);\n \n@@ -287,6 +294,7 @@ void coroutine_fn monitor_qmp_dispatcher_co(void *data)\n */\n \n mon = req_obj->mon;\n+ qmp_dispatcher_current_mon = mon;\n \n /*\n * We need to resume the monitor if handle_qmp_command()\n@@ -347,6 +355,16 @@ void coroutine_fn monitor_qmp_dispatcher_co(void *data)\n }\n \n qmp_request_free(req_obj);\n+\n+ /*\n+ * If monitor-remove was called while we were dispatching a\n+ * request on this monitor, the monitor was marked dead and\n+ * removed from mon_list but destruction was deferred to us.\n+ */\n+ if (mon->common.dead) {\n+ monitor_qmp_destroy(mon);\n+ }\n+ qmp_dispatcher_current_mon = NULL;\n }\n qatomic_set(&qmp_dispatcher_co, NULL);\n }\n@@ -499,6 +517,22 @@ void monitor_data_destroy_qmp(MonitorQMP *mon)\n g_queue_free(mon->qmp_requests);\n }\n \n+/*\n+ * Destroy a single dynamically-added QMP monitor.\n+ * The monitor must already have been removed from mon_list.\n+ */\n+void monitor_qmp_destroy(MonitorQMP *mon)\n+{\n+ monitor_flush(&mon->common);\n+ monitor_data_destroy(&mon->common);\n+ g_free(mon);\n+}\n+\n+bool monitor_qmp_dispatcher_is_servicing(MonitorQMP *mon)\n+{\n+ return qmp_dispatcher_current_mon == mon;\n+}\n+\n static void monitor_qmp_setup_handlers_bh(void *opaque)\n {\n MonitorQMP *mon = opaque;\n", "prefixes": [ "2/5" ] }