[PATCH v3 00/10] QOM: container_get() removal

[PATCH v3 00/10] QOM: container_get() removal

[Philippe Mathieu-Daudé]

Respin of Peter's v2:
https://lore.kernel.org/qemu-devel/20241121192202.4155849-1-peterx@redhat.com/

'The series is about container_get() and its removal.'
(See v2's cover).

Since v2:
- Create fake machine container for user emulation to avoid:

  $ ./qemu-x86_64 /bin/echo foo
  qemu-x86_64: ../../hw/core/qdev.c:825: qdev_get_machine: Assertion `dev' failed.
  Aborted (core dumped)

Peter Xu (6):
  qdev: Make qdev_get_machine() not use container_get()
  qdev: Add machine_get_container()
  qdev: Use machine_get_container()
  qom: Add object_get_container()
  qom: Use object_get_container()
  qom: Remove container_get()

Philippe Mathieu-Daudé (4):
  qdev: Expose qemu_create_machine()
  qdev: Implement qemu_create_machine() for user emulation
  qdev: Call qemu_create_machine() on user emulation
  qdev: Inline machine_containers[] in qemu_create_machine_containers()

 include/hw/qdev-core.h    | 12 ++++++++++++
 include/qom/object.h      | 21 ++++++++++-----------
 accel/tcg/tcg-all.c       |  8 +++++++-
 backends/cryptodev.c      |  4 ++--
 chardev/char.c            |  2 +-
 hw/core/gpio.c            |  3 +--
 hw/core/qdev-user-stubs.c | 11 +++++++++++
 hw/core/qdev.c            | 21 ++++++++++++++++++---
 hw/core/sysbus.c          |  4 ++--
 hw/i386/pc.c              |  4 ++--
 qom/container.c           | 23 -----------------------
 qom/object.c              | 12 +++++++++++-
 scsi/pr-manager.c         |  4 ++--
 system/ioport.c           |  2 +-
 system/memory.c           |  2 +-
 system/qdev-monitor.c     |  6 +++---
 system/vl.c               | 20 +++++++++-----------
 ui/console.c              |  2 +-
 ui/dbus-chardev.c         |  2 +-
 hw/core/meson.build       |  1 +
 20 files changed, 96 insertions(+), 68 deletions(-)
 create mode 100644 hw/core/qdev-user-stubs.c

-- 
2.47.1

[PATCH v3 01/10] qdev: Expose qemu_create_machine()

[Philippe Mathieu-Daudé]

We need to create a 'fake' machine container for the
QOM API. We already have the system implementation
for qemu_create_machine(). Expose its prototype to
be able to add the user implementation.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/hw/qdev-core.h | 2 ++
 system/vl.c            | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index e6ef80b7fd0..bf8a0ee6486 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -1106,6 +1106,8 @@ void device_listener_unregister(DeviceListener *listener);
  */
 bool qdev_should_hide_device(const QDict *opts, bool from_json, Error **errp);
 
+void qemu_create_machine(QDict *qdict);
+
 typedef enum MachineInitPhase {
     /* current_machine is NULL.  */
     PHASE_NO_MACHINE,
diff --git a/system/vl.c b/system/vl.c
index 0843b7ab49b..33fbb9f32f3 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -28,6 +28,7 @@
 #include "qemu/units.h"
 #include "exec/cpu-common.h"
 #include "exec/page-vary.h"
+#include "hw/qdev-core.h"
 #include "hw/qdev-properties.h"
 #include "qapi/compat-policy.h"
 #include "qapi/error.h"
@@ -2128,7 +2129,7 @@ static void qemu_create_machine_containers(Object *machine)
     }
 }
 
-static void qemu_create_machine(QDict *qdict)
+void qemu_create_machine(QDict *qdict)
 {
     MachineClass *machine_class = select_machine(qdict, &error_fatal);
     object_set_machine_compat_props(machine_class->compat_props);
-- 
2.47.1

[PATCH v3 02/10] qdev: Implement qemu_create_machine() for user emulation

[Philippe Mathieu-Daudé]

To satisfy QOM containers design, implement qemu_create_machine()
for user emulation, creating a 'fake' machine.

Suggested-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/core/qdev-user-stubs.c | 11 +++++++++++
 hw/core/meson.build       |  1 +
 2 files changed, 12 insertions(+)
 create mode 100644 hw/core/qdev-user-stubs.c

diff --git a/hw/core/qdev-user-stubs.c b/hw/core/qdev-user-stubs.c
new file mode 100644
index 00000000000..9d481a61dbf
--- /dev/null
+++ b/hw/core/qdev-user-stubs.c
@@ -0,0 +1,11 @@
+#include "qemu/osdep.h"
+#include "hw/qdev-core.h"
+
+void qemu_create_machine(QDict *qdict)
+{
+    Object *fake_machine_obj;
+
+    fake_machine_obj = object_property_add_new_container(object_get_root(),
+                                                         "machine");
+    object_property_add_new_container(fake_machine_obj, "unattached");
+}
diff --git a/hw/core/meson.build b/hw/core/meson.build
index ce9dfa3f4bf..0f020fed1df 100644
--- a/hw/core/meson.build
+++ b/hw/core/meson.build
@@ -46,3 +46,4 @@ system_ss.add(files(
   'vm-change-state-handler.c',
   'clock-vmstate.c',
 ))
+user_ss.add(files('qdev-user-stubs.c'))
-- 
2.47.1

Re: [PATCH v3 02/10] qdev: Implement qemu_create_machine() for user emulation

[Philippe Mathieu-Daudé]

On 2/1/25 16:12, Philippe Mathieu-Daudé wrote:
> To satisfy QOM containers design, implement qemu_create_machine()
> for user emulation, creating a 'fake' machine.
> 
> Suggested-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   hw/core/qdev-user-stubs.c | 11 +++++++++++
>   hw/core/meson.build       |  1 +
>   2 files changed, 12 insertions(+)
>   create mode 100644 hw/core/qdev-user-stubs.c
> 
> diff --git a/hw/core/qdev-user-stubs.c b/hw/core/qdev-user-stubs.c
> new file mode 100644
> index 00000000000..9d481a61dbf
> --- /dev/null
> +++ b/hw/core/qdev-user-stubs.c
> @@ -0,0 +1,11 @@

   /* SPDX-License-Identifier: GPL-2.0-or-later */

> +#include "qemu/osdep.h"
> +#include "hw/qdev-core.h"
> +
> +void qemu_create_machine(QDict *qdict)
> +{
> +    Object *fake_machine_obj;
> +
> +    fake_machine_obj = object_property_add_new_container(object_get_root(),
> +                                                         "machine");
> +    object_property_add_new_container(fake_machine_obj, "unattached");
> +}
> diff --git a/hw/core/meson.build b/hw/core/meson.build
> index ce9dfa3f4bf..0f020fed1df 100644
> --- a/hw/core/meson.build
> +++ b/hw/core/meson.build
> @@ -46,3 +46,4 @@ system_ss.add(files(
>     'vm-change-state-handler.c',
>     'clock-vmstate.c',
>   ))
> +user_ss.add(files('qdev-user-stubs.c'))

[PATCH v3 03/10] qdev: Call qemu_create_machine() on user emulation

[Philippe Mathieu-Daudé]

For system emulation, qemu_create_machine() is
called from qemu_init().
TCG accelerator always calls tcg_init_machine().
Use it to call qemu_create_machine() on user
emulation.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 accel/tcg/tcg-all.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
index c2565758876..e18b0c03f71 100644
--- a/accel/tcg/tcg-all.c
+++ b/accel/tcg/tcg-all.c
@@ -35,7 +35,9 @@
 #include "qemu/atomic.h"
 #include "qapi/qapi-builtin-visit.h"
 #include "qemu/units.h"
-#if !defined(CONFIG_USER_ONLY)
+#if defined(CONFIG_USER_ONLY)
+#include "hw/qdev-core.h"
+#else
 #include "hw/boards.h"
 #endif
 #include "internal-common.h"
@@ -124,6 +126,10 @@ static int tcg_init_machine(MachineState *ms)
     tcg_prologue_init();
 #endif
 
+#ifdef CONFIG_USER_ONLY
+    qemu_create_machine(NULL);
+#endif
+
     return 0;
 }
 
-- 
2.47.1

[PATCH v3 04/10] qdev: Make qdev_get_machine() not use container_get()

[Philippe Mathieu-Daudé]

From: Peter Xu <peterx@redhat.com>

Currently, qdev_get_machine() has a slight misuse on container_get(), as
the helper says "get a container" but in reality the goal is to get the
machine object.  It is still a "container" but not strictly.

Note that it _may_ get a container (at "/machine") in our current unit test
of test-qdev-global-props.c before all these changes, but it's probably
unexpected and worked by accident.

Switch to an explicit object_resolve_path_component(), with a side benefit
that qdev_get_machine() can happen a lot, and we don't need to split the
string ("/machine") every time.  This also paves way for making the helper
container_get() never try to return a non-container at all.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241121192202.4155849-9-peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/core/qdev.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 57c1d9df3a7..bc5b60212a7 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -818,7 +818,12 @@ Object *qdev_get_machine(void)
     static Object *dev;
 
     if (dev == NULL) {
-        dev = container_get(object_get_root(), "/machine");
+        dev = object_resolve_path_component(object_get_root(), "machine");
+        /*
+         * Any call to this function before machine is created is treated
+         * as a programming error as of now.
+         */
+        assert(dev);
     }
 
     return dev;
-- 
2.47.1

[PATCH v3 05/10] qdev: Add machine_get_container()

[Philippe Mathieu-Daudé]

From: Peter Xu <peterx@redhat.com>

Add a helper to fetch machine containers.  Add some sanity check around.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-ID: <20241121192202.4155849-10-peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/hw/qdev-core.h | 10 ++++++++++
 hw/core/qdev.c         | 11 +++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index bf8a0ee6486..bb4b085c9ce 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -1027,6 +1027,16 @@ const char *qdev_fw_name(DeviceState *dev);
 void qdev_assert_realized_properly(void);
 Object *qdev_get_machine(void);
 
+/**
+ * machine_get_container:
+ * @name: The name of container to lookup
+ *
+ * Get a container of the machine (QOM path "/machine/NAME").
+ *
+ * Returns: the machine container object.
+ */
+Object *machine_get_container(const char *name);
+
 /**
  * qdev_get_human_name() - Return a human-readable name for a device
  * @dev: The device. Must be a valid and non-NULL pointer.
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index bc5b60212a7..9973e029ffa 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -829,6 +829,17 @@ Object *qdev_get_machine(void)
     return dev;
 }
 
+Object *machine_get_container(const char *name)
+{
+    Object *container, *machine;
+
+    machine = qdev_get_machine();
+    container = object_resolve_path_component(machine, name);
+    assert(object_dynamic_cast(container, TYPE_CONTAINER));
+
+    return container;
+}
+
 char *qdev_get_human_name(DeviceState *dev)
 {
     g_assert(dev != NULL);
-- 
2.47.1

[PATCH v3 06/10] qdev: Use machine_get_container()

[Philippe Mathieu-Daudé]

From: Peter Xu <peterx@redhat.com>

Use machine_get_container() whenever applicable across the tree.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241121192202.4155849-11-peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/core/gpio.c        | 3 +--
 hw/core/qdev.c        | 3 +--
 hw/core/sysbus.c      | 4 ++--
 hw/i386/pc.c          | 4 ++--
 system/ioport.c       | 2 +-
 system/memory.c       | 2 +-
 system/qdev-monitor.c | 6 +++---
 system/vl.c           | 3 +--
 8 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/hw/core/gpio.c b/hw/core/gpio.c
index 80d07a6ec99..6e32a8eec61 100644
--- a/hw/core/gpio.c
+++ b/hw/core/gpio.c
@@ -121,8 +121,7 @@ void qdev_connect_gpio_out_named(DeviceState *dev, const char *name, int n,
                                      name ? name : "unnamed-gpio-out", n);
     if (input_pin && !OBJECT(input_pin)->parent) {
         /* We need a name for object_property_set_link to work */
-        object_property_add_child(container_get(qdev_get_machine(),
-                                                "/unattached"),
+        object_property_add_child(machine_get_container("unattached"),
                                   "non-qdev-gpio[*]", OBJECT(input_pin));
     }
     object_property_set_link(OBJECT(dev), propname,
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 9973e029ffa..cfdb7beca24 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -476,8 +476,7 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
         if (!obj->parent) {
             gchar *name = g_strdup_printf("device[%d]", unattached_count++);
 
-            object_property_add_child(container_get(qdev_get_machine(),
-                                                    "/unattached"),
+            object_property_add_child(machine_get_container("unattached"),
                                       name, obj);
             unattached_parent = true;
             g_free(name);
diff --git a/hw/core/sysbus.c b/hw/core/sysbus.c
index e64d99c8edf..9355849ff0a 100644
--- a/hw/core/sysbus.c
+++ b/hw/core/sysbus.c
@@ -65,9 +65,9 @@ void foreach_dynamic_sysbus_device(FindSysbusDeviceFunc *func, void *opaque)
     };
 
     /* Loop through all sysbus devices that were spawned outside the machine */
-    container = container_get(qdev_get_machine(), "/peripheral");
+    container = machine_get_container("peripheral");
     find_sysbus_device(container, &find);
-    container = container_get(qdev_get_machine(), "/peripheral-anon");
+    container = machine_get_container("peripheral-anon");
     find_sysbus_device(container, &find);
 }
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 71118765884..9334b033f65 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -463,7 +463,7 @@ static int check_fdc(Object *obj, void *opaque)
 }
 
 static const char * const fdc_container_path[] = {
-    "/unattached", "/peripheral", "/peripheral-anon"
+    "unattached", "peripheral", "peripheral-anon"
 };
 
 /*
@@ -477,7 +477,7 @@ static ISADevice *pc_find_fdc0(void)
     CheckFdcState state = { 0 };
 
     for (i = 0; i < ARRAY_SIZE(fdc_container_path); i++) {
-        container = container_get(qdev_get_machine(), fdc_container_path[i]);
+        container = machine_get_container(fdc_container_path[i]);
         object_child_foreach(container, check_fdc, &state);
     }
 
diff --git a/system/ioport.c b/system/ioport.c
index fd551d0375e..55c2a752396 100644
--- a/system/ioport.c
+++ b/system/ioport.c
@@ -258,7 +258,7 @@ static void portio_list_add_1(PortioList *piolist,
     object_ref(&mrpio->mr);
     object_unparent(OBJECT(&mrpio->mr));
     if (!piolist->owner) {
-        owner = container_get(qdev_get_machine(), "/unattached");
+        owner = machine_get_container("unattached");
     } else {
         owner = piolist->owner;
     }
diff --git a/system/memory.c b/system/memory.c
index 78e17e0efa8..b17b5538ffa 100644
--- a/system/memory.c
+++ b/system/memory.c
@@ -1238,7 +1238,7 @@ static void memory_region_do_init(MemoryRegion *mr,
         char *name_array = g_strdup_printf("%s[*]", escaped_name);
 
         if (!owner) {
-            owner = container_get(qdev_get_machine(), "/unattached");
+            owner = machine_get_container("unattached");
         }
 
         object_property_add_child(owner, name_array, OBJECT(mr));
diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index c844f538025..7f4a1f5083b 100644
--- a/system/qdev-monitor.c
+++ b/system/qdev-monitor.c
@@ -348,7 +348,7 @@ static Object *qdev_get_peripheral(void)
     static Object *dev;
 
     if (dev == NULL) {
-        dev = container_get(qdev_get_machine(), "/peripheral");
+        dev = machine_get_container("peripheral");
     }
 
     return dev;
@@ -359,7 +359,7 @@ static Object *qdev_get_peripheral_anon(void)
     static Object *dev;
 
     if (dev == NULL) {
-        dev = container_get(qdev_get_machine(), "/peripheral-anon");
+        dev = machine_get_container("peripheral-anon");
     }
 
     return dev;
@@ -1098,7 +1098,7 @@ static GSList *qdev_build_hotpluggable_device_list(Object *peripheral)
 static void peripheral_device_del_completion(ReadLineState *rs,
                                              const char *str)
 {
-    Object *peripheral = container_get(qdev_get_machine(), "/peripheral");
+    Object *peripheral = machine_get_container("peripheral");
     GSList *list, *item;
 
     list = qdev_build_hotpluggable_device_list(peripheral);
diff --git a/system/vl.c b/system/vl.c
index 33fbb9f32f3..933ad83a935 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -2138,8 +2138,7 @@ void qemu_create_machine(QDict *qdict)
     object_property_add_child(object_get_root(), "machine",
                               OBJECT(current_machine));
     qemu_create_machine_containers(OBJECT(current_machine));
-    object_property_add_child(container_get(OBJECT(current_machine),
-                                            "/unattached"),
+    object_property_add_child(machine_get_container("unattached"),
                               "sysbus", OBJECT(sysbus_get_default()));
 
     if (machine_class->minimum_page_bits) {
-- 
2.47.1

[PATCH v3 07/10] qom: Add object_get_container()

[Philippe Mathieu-Daudé]

From: Peter Xu <peterx@redhat.com>

Add a helper to fetch a root container (under object_get_root()).  Sanity
check on the type of the object.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-ID: <20241121192202.4155849-12-peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/qom/object.h | 10 ++++++++++
 qom/object.c         | 10 ++++++++++
 2 files changed, 20 insertions(+)

diff --git a/include/qom/object.h b/include/qom/object.h
index 95d6e064d9b..bcf9910b42c 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -1510,6 +1510,16 @@ const char *object_property_get_type(Object *obj, const char *name,
  */
 Object *object_get_root(void);
 
+/**
+ * object_get_container:
+ * @name: the name of container to lookup
+ *
+ * Lookup a root level container.
+ *
+ * Returns: the container with @name.
+ */
+Object *object_get_container(const char *name);
+
 
 /**
  * object_get_objects_root:
diff --git a/qom/object.c b/qom/object.c
index b4c52d055d9..81c06906d30 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1751,6 +1751,16 @@ static Object *object_root_initialize(void)
     return root;
 }
 
+Object *object_get_container(const char *name)
+{
+    Object *container;
+
+    container = object_resolve_path_component(object_get_root(), name);
+    assert(object_dynamic_cast(container, TYPE_CONTAINER));
+
+    return container;
+}
+
 Object *object_get_root(void)
 {
     static Object *root;
-- 
2.47.1

[PATCH v3 08/10] qom: Use object_get_container()

[Philippe Mathieu-Daudé]

From: Peter Xu <peterx@redhat.com>

Use object_get_container() whenever applicable across the tree.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241121192202.4155849-13-peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 backends/cryptodev.c | 4 ++--
 chardev/char.c       | 2 +-
 qom/object.c         | 2 +-
 scsi/pr-manager.c    | 4 ++--
 ui/console.c         | 2 +-
 ui/dbus-chardev.c    | 2 +-
 6 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/backends/cryptodev.c b/backends/cryptodev.c
index 1157a149d02..1187b08dacf 100644
--- a/backends/cryptodev.c
+++ b/backends/cryptodev.c
@@ -97,7 +97,7 @@ static int qmp_query_cryptodev_foreach(Object *obj, void *data)
 QCryptodevInfoList *qmp_query_cryptodev(Error **errp)
 {
     QCryptodevInfoList *list = NULL;
-    Object *objs = container_get(object_get_root(), "/objects");
+    Object *objs = object_get_container("objects");
 
     object_child_foreach(objs, qmp_query_cryptodev_foreach, &list);
 
@@ -557,7 +557,7 @@ static void cryptodev_backend_stats_cb(StatsResultList **result,
     switch (target) {
     case STATS_TARGET_CRYPTODEV:
     {
-        Object *objs = container_get(object_get_root(), "/objects");
+        Object *objs = object_get_container("objects");
         StatsArgs stats_args;
         stats_args.result.stats = result;
         stats_args.names = names;
diff --git a/chardev/char.c b/chardev/char.c
index 44ff116fcda..7705da5ad02 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -48,7 +48,7 @@
 
 Object *get_chardevs_root(void)
 {
-    return container_get(object_get_root(), "/chardevs");
+    return object_get_container("chardevs");
 }
 
 static void chr_be_event(Chardev *s, QEMUChrEvent event)
diff --git a/qom/object.c b/qom/object.c
index 81c06906d30..58897a79a76 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1774,7 +1774,7 @@ Object *object_get_root(void)
 
 Object *object_get_objects_root(void)
 {
-    return container_get(object_get_root(), "/objects");
+    return object_get_container("objects");
 }
 
 Object *object_get_internal_root(void)
diff --git a/scsi/pr-manager.c b/scsi/pr-manager.c
index fb5fc297309..1977d99ce0d 100644
--- a/scsi/pr-manager.c
+++ b/scsi/pr-manager.c
@@ -21,7 +21,7 @@
 #include "qemu/module.h"
 #include "qapi/qapi-commands-block.h"
 
-#define PR_MANAGER_PATH     "/objects"
+#define PR_MANAGER_PATH     "objects"
 
 typedef struct PRManagerData {
     PRManager *pr_mgr;
@@ -135,7 +135,7 @@ PRManagerInfoList *qmp_query_pr_managers(Error **errp)
 {
     PRManagerInfoList *head = NULL;
     PRManagerInfoList **prev = &head;
-    Object *container = container_get(object_get_root(), PR_MANAGER_PATH);
+    Object *container = object_get_container(PR_MANAGER_PATH);
 
     object_child_foreach(container, query_one_pr_manager, &prev);
     return head;
diff --git a/ui/console.c b/ui/console.c
index 5165f171257..914ed2cc76b 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -1160,7 +1160,7 @@ DisplayState *init_displaystate(void)
          * all QemuConsoles are created and the order / numbering
          * doesn't change any more */
         name = g_strdup_printf("console[%d]", con->index);
-        object_property_add_child(container_get(object_get_root(), "/backend"),
+        object_property_add_child(object_get_container("backend"),
                                   name, OBJECT(con));
         g_free(name);
     }
diff --git a/ui/dbus-chardev.c b/ui/dbus-chardev.c
index 1d3a7122a11..bf061cbc930 100644
--- a/ui/dbus-chardev.c
+++ b/ui/dbus-chardev.c
@@ -106,7 +106,7 @@ dbus_chardev_init(DBusDisplay *dpy)
     dpy->notifier.notify = dbus_display_on_notify;
     dbus_display_notifier_add(&dpy->notifier);
 
-    object_child_foreach(container_get(object_get_root(), "/chardevs"),
+    object_child_foreach(object_get_container("chardevs"),
                          dbus_display_chardev_foreach, dpy);
 }
 
-- 
2.47.1

[PATCH v3 09/10] qom: Remove container_get()

[Philippe Mathieu-Daudé]

From: Peter Xu <peterx@redhat.com>

Now there's no user of container_get(), remove it.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241121192202.4155849-14-peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/qom/object.h | 11 -----------
 qom/container.c      | 23 -----------------------
 2 files changed, 34 deletions(-)

diff --git a/include/qom/object.h b/include/qom/object.h
index bcf9910b42c..77935572894 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -2017,17 +2017,6 @@ int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),
 int object_child_foreach_recursive(Object *obj,
                                    int (*fn)(Object *child, void *opaque),
                                    void *opaque);
-/**
- * container_get:
- * @root: root of the #path, e.g., object_get_root()
- * @path: path to the container
- *
- * Return a container object whose path is @path.  Create more containers
- * along the path if necessary.
- *
- * Returns: the container object.
- */
-Object *container_get(Object *root, const char *path);
 
 /**
  * object_property_add_new_container:
diff --git a/qom/container.c b/qom/container.c
index 20ab74b0e8d..38a27ec1edd 100644
--- a/qom/container.c
+++ b/qom/container.c
@@ -34,27 +34,4 @@ Object *object_property_add_new_container(Object *obj, const char *name)
     return child;
 }
 
-Object *container_get(Object *root, const char *path)
-{
-    Object *obj, *child;
-    char **parts;
-    int i;
-
-    parts = g_strsplit(path, "/", 0);
-    assert(parts != NULL && parts[0] != NULL && !parts[0][0]);
-    obj = root;
-
-    for (i = 1; parts[i] != NULL; i++, obj = child) {
-        child = object_resolve_path_component(obj, parts[i]);
-        if (!child) {
-            child = object_property_add_new_container(obj, parts[i]);
-        }
-    }
-
-    g_strfreev(parts);
-
-    return obj;
-}
-
-
 type_init(container_register_types)
-- 
2.47.1

[PATCH v3 10/10] qdev: Inline machine_containers[] in qemu_create_machine_containers()

[Philippe Mathieu-Daudé]

Only qemu_create_machine_containers() uses the
machine_containers[] array, restrict the scope
to this single user.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 system/vl.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/system/vl.c b/system/vl.c
index 933ad83a935..58e68b98d87 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -2114,17 +2114,15 @@ static void parse_memory_options(void)
     loc_pop(&loc);
 }
 
-static const char *const machine_containers[] = {
-    "unattached",
-    "peripheral",
-    "peripheral-anon"
-};
-
 static void qemu_create_machine_containers(Object *machine)
 {
-    int i;
+    static const char *const machine_containers[] = {
+        "unattached",
+        "peripheral",
+        "peripheral-anon"
+    };
 
-    for (i = 0; i < ARRAY_SIZE(machine_containers); i++) {
+    for (unsigned i = 0; i < ARRAY_SIZE(machine_containers); i++) {
         object_property_add_new_container(machine, machine_containers[i]);
     }
 }
-- 
2.47.1

Re: [PATCH v3 00/10] QOM: container_get() removal

[Peter Xu]

On Thu, Jan 02, 2025 at 04:12:34PM +0100, Philippe Mathieu-Daudé wrote:
> Philippe Mathieu-Daudé (4):
>   qdev: Expose qemu_create_machine()
>   qdev: Implement qemu_create_machine() for user emulation
>   qdev: Call qemu_create_machine() on user emulation
>   qdev: Inline machine_containers[] in qemu_create_machine_containers()

For these four, all look fine to me, feel free to take:

Acked-by: Peter Xu <peterx@redhat.com>

Said that, still one comment: maybe we don't need to make the function
qemu_create_machine() to be an user+system API?  Instead we could have
user_ss defines qemu_create_fake_machine() and invoke it iff USER_ONLY, the
same as what patch 3 does.  Then we can drop patch 1, because exporting
system's qemu_create_machine() isn't required, IIUC.

We could add some comment above USER_ONLY's qemu_create_[fake_]machine() on
why the fake machine is created (qdev_realize() of cpu devices relies on
machine object, etc.).  It might still be helpful hint so that we know it
can be dropped if qdev_realize() doesn't need to rely on machine one day.

Thanks,

-- 
Peter Xu

Re: [PATCH v3 00/10] QOM: container_get() removal

[Philippe Mathieu-Daudé]

On 2/1/25 18:29, Peter Xu wrote:
> On Thu, Jan 02, 2025 at 04:12:34PM +0100, Philippe Mathieu-Daudé wrote:
>> Philippe Mathieu-Daudé (4):
>>    qdev: Expose qemu_create_machine()
>>    qdev: Implement qemu_create_machine() for user emulation
>>    qdev: Call qemu_create_machine() on user emulation
>>    qdev: Inline machine_containers[] in qemu_create_machine_containers()
> 
> For these four, all look fine to me, feel free to take:
> 
> Acked-by: Peter Xu <peterx@redhat.com>
> 
> Said that, still one comment: maybe we don't need to make the function
> qemu_create_machine() to be an user+system API?  Instead we could have
> user_ss defines qemu_create_fake_machine() and invoke it iff USER_ONLY, the
> same as what patch 3 does.  Then we can drop patch 1, because exporting
> system's qemu_create_machine() isn't required, IIUC.

Good idea (not easy because -- again -- CONFIG_USER_ONLY isn't defined).

> We could add some comment above USER_ONLY's qemu_create_[fake_]machine() on
> why the fake machine is created (qdev_realize() of cpu devices relies on
> machine object, etc.).  It might still be helpful hint so that we know it
> can be dropped if qdev_realize() doesn't need to rely on machine one day.
> 
> Thanks,
>