[PATCH v4 05/35] monitor: minimal conversion of monitors to QOM

23 Jun 2026

This introduces a Monitor QOM object, with MonitorHMP and
MonitorQMP subclasses. This is the bare minimum conversion
of just the type declarations and replacing g_new/g_free
with object_new/object_unref.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 include/monitor/monitor.h  | 11 ++++++++++-
 monitor/hmp.c              | 29 +++++++++++++++++++++++++++--
 monitor/monitor-internal.h | 18 ++++++++++++++++--
 monitor/monitor.c          | 18 ++++++++++++++++--
 monitor/qmp-cmds.c         | 15 ++++++++-------
 monitor/qmp.c              | 29 +++++++++++++++++++++++++++--
 6 files changed, 104 insertions(+), 16 deletions(-)

diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
index b9642b58ba..2e9f9e12e9 100644
--- a/include/monitor/monitor.h
+++ b/include/monitor/monitor.h
@@ -5,8 +5,17 @@
 #include "qapi/qapi-types-misc.h"
 #include "qemu/readline.h"
 #include "exec/hwaddr.h"
+#include "qom/object.h"
+
+#define TYPE_MONITOR "monitor"
+OBJECT_DECLARE_TYPE(Monitor, MonitorClass, MONITOR);
+
+#define TYPE_MONITOR_HMP "monitor-hmp"
+OBJECT_DECLARE_TYPE(MonitorHMP, MonitorHMPClass, MONITOR_HMP);
+
+#define TYPE_MONITOR_QMP "monitor-qmp"
+OBJECT_DECLARE_TYPE(MonitorQMP, MonitorQMPClass, MONITOR_QMP);
 
-typedef struct MonitorHMP MonitorHMP;
 typedef struct MonitorOptions MonitorOptions;
 
 #define QMP_REQ_QUEUE_LEN_MAX 8
diff --git a/monitor/hmp.c b/monitor/hmp.c
index 4e4468424a..81047d2513 100644
--- a/monitor/hmp.c
+++ b/monitor/hmp.c
@@ -43,6 +43,20 @@
 #include "system/block-backend.h"
 #include "trace.h"
 
+OBJECT_DEFINE_TYPE(MonitorHMP, monitor_hmp, MONITOR_HMP, MONITOR);
+
+static void monitor_hmp_finalize(Object *obj)
+{
+}
+
+static void monitor_hmp_class_init(ObjectClass *cls, const void *data)
+{
+}
+
+static void monitor_hmp_init(Object *obj)
+{
+}
+
 static void monitor_command_cb(void *opaque, const char *cmdline,
                                void *readline_opaque)
 {
@@ -1526,10 +1540,21 @@ static void monitor_readline_flush(void *opaque)
 
 void monitor_new_hmp(Chardev *chr, bool use_readline, Error **errp)
 {
-    MonitorHMP *mon = g_new0(MonitorHMP, 1);
+    MonitorHMP *mon;
+    static int counter;
+    g_autofree char *id = g_strdup_printf("hmpcompat%d", counter++);
+    Object *obj = object_new_with_props(TYPE_MONITOR_HMP,
+                                        object_get_objects_root(),
+                                        id,
+                                        errp,
+                                        NULL);
+    if (!obj) {
+        return;
+    }
+    mon = MONITOR_HMP(obj);
 
     if (!qemu_chr_fe_init(&mon->parent_obj.chr, chr, errp)) {
-        g_free(mon);
+        object_unparent(OBJECT(mon));
         return;
     }
 
diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h
index 4da2b2a677..05c1f2f5e0 100644
--- a/monitor/monitor-internal.h
+++ b/monitor/monitor-internal.h
@@ -101,7 +101,13 @@ typedef struct HMPCommand {
     bool coroutine;
 } HMPCommand;
 
+
+struct MonitorClass {
+    ObjectClass parent_class;
+};
+
 struct Monitor {
+    Object parent;
     CharFrontend chr;
     int suspend_cnt;            /* Needs to be accessed atomically */
     bool is_qmp;
@@ -127,6 +133,10 @@ struct Monitor {
     int reset_seen;
 };
 
+struct MonitorHMPClass {
+    MonitorClass parent_class;
+};
+
 struct MonitorHMP {
     Monitor parent_obj;
     bool use_readline;
@@ -140,7 +150,11 @@ struct MonitorHMP {
     ReadLineState *rs;
 };
 
-typedef struct {
+struct MonitorQMPClass {
+    MonitorClass parent_class;
+};
+
+struct MonitorQMP {
     Monitor parent_obj;
     JSONMessageParser parser;
     bool pretty;
@@ -160,7 +174,7 @@ typedef struct {
     QemuMutex qmp_queue_lock;
     /* Input queue that holds all the parsed QMP requests */
     GQueue *qmp_requests;
-} MonitorQMP;
+};
 
 /**
  * Is @mon a QMP monitor?
diff --git a/monitor/monitor.c b/monitor/monitor.c
index a87597e606..a497c25c54 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -73,6 +73,20 @@ static GHashTable *coroutine_mon; /* Maps Coroutine* to Monitor* */
 MonitorList mon_list;
 static bool monitor_destroyed;
 
+OBJECT_DEFINE_TYPE(Monitor, monitor, MONITOR, OBJECT);
+
+static void monitor_finalize(Object *obj)
+{
+}
+
+static void monitor_class_init(ObjectClass *cls, const void *data)
+{
+}
+
+static void monitor_init(Object *obj)
+{
+}
+
 Monitor *monitor_cur(void)
 {
     Monitor *mon;
@@ -598,7 +612,7 @@ void monitor_list_append(Monitor *mon)
 
     if (mon) {
         monitor_data_destroy(mon);
-        g_free(mon);
+        object_unparent(OBJECT(mon));
     }
 }
 
@@ -680,7 +694,7 @@ void monitor_cleanup(void)
         monitor_flush(mon);
         monitor_data_destroy(mon);
         qemu_mutex_lock(&monitor_lock);
-        g_free(mon);
+        object_unparent(OBJECT(mon));
     }
     qemu_mutex_unlock(&monitor_lock);
 
diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index aa9ee8a391..bfde769ef0 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -166,12 +166,12 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
                                 int64_t cpu_index, Error **errp)
 {
     char *output = NULL;
-    MonitorHMP hmp = {};
+    MonitorHMP *hmp = MONITOR_HMP(object_new(TYPE_MONITOR_HMP));
 
-    monitor_data_init(&hmp.parent_obj, false, true, false);
+    monitor_data_init(&hmp->parent_obj, false, true, false);
 
     if (has_cpu_index) {
-        int ret = monitor_set_cpu(&hmp.parent_obj, cpu_index);
+        int ret = monitor_set_cpu(&hmp->parent_obj, cpu_index);
         if (ret < 0) {
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cpu-index",
                        "a CPU number");
@@ -179,14 +179,15 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
         }
     }
 
-    handle_hmp_command(&hmp, command_line);
+    handle_hmp_command(hmp, command_line);
 
-    WITH_QEMU_LOCK_GUARD(&hmp.parent_obj.mon_lock) {
-        output = g_strdup(hmp.parent_obj.outbuf->str);
+    WITH_QEMU_LOCK_GUARD(&hmp->parent_obj.mon_lock) {
+        output = g_strdup(hmp->parent_obj.outbuf->str);
     }
 
 out:
-    monitor_data_destroy(&hmp.parent_obj);
+    monitor_data_destroy(&hmp->parent_obj);
+    object_unref(hmp);
     return output;
 }
 
diff --git a/monitor/qmp.c b/monitor/qmp.c
index cb28a95efd..5231ed506a 100644
--- a/monitor/qmp.c
+++ b/monitor/qmp.c
@@ -71,6 +71,20 @@ typedef struct QMPRequest QMPRequest;
 
 QmpCommandList qmp_commands, qmp_cap_negotiation_commands;
 
+OBJECT_DEFINE_TYPE(MonitorQMP, monitor_qmp, MONITOR_QMP, MONITOR);
+
+static void monitor_qmp_finalize(Object *obj)
+{
+}
+
+static void monitor_qmp_class_init(ObjectClass *cls, const void *data)
+{
+}
+
+static void monitor_qmp_init(Object *obj)
+{
+}
+
 static bool qmp_oob_enabled(MonitorQMP *mon)
 {
     return mon->capab[QMP_CAPABILITY_OOB];
@@ -515,10 +529,21 @@ static void monitor_qmp_setup_handlers_bh(void *opaque)
 
 void monitor_new_qmp(Chardev *chr, bool pretty, Error **errp)
 {
-    MonitorQMP *mon = g_new0(MonitorQMP, 1);
+    MonitorQMP *mon;
+    static int counter;
+    g_autofree char *id = g_strdup_printf("qmpcompat%d", counter++);
+    Object *obj = object_new_with_props(TYPE_MONITOR_QMP,
+                                        object_get_objects_root(),
+                                        id,
+                                        errp,
+                                        NULL);
+    if (!obj) {
+        return;
+    }
+    mon = MONITOR_QMP(obj);
 
     if (!qemu_chr_fe_init(&mon->parent_obj.chr, chr, errp)) {
-        g_free(mon);
+        object_unparent(OBJECT(mon));
         return;
     }
     qemu_chr_fe_set_echo(&mon->parent_obj.chr, true);
-- 
2.54.0

    