[Qemu-devel] [PATCH v3 7/7] qdev: drop misleading qdev_free() function

[Stefan Hajnoczi <stefanha@redhat.com>]

The qdev_free() function name is misleading since all the function does
is unlink the device from its parent.  The device is not necessarily
freed.

The device will be freed when its QObject refcount reaches zero.  It is
usual for the parent (bus) to hold the final reference but there are
cases where something else holds a reference so "free" is a misleading
name.

Call object_unparent(obj) directly instead of having a qdev wrapper
function.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/acpi/piix4.c          |  2 +-
 hw/core/qdev.c           | 12 +++---------
 hw/pci/pci-hotplug-old.c |  2 +-
 hw/pci/pci_bridge.c      |  2 +-
 hw/pci/pcie.c            |  2 +-
 hw/pci/shpc.c            |  2 +-
 hw/s390x/virtio-ccw.c    |  2 +-
 hw/scsi/scsi-bus.c       |  6 +++---
 hw/usb/bus.c             |  7 ++++---
 hw/usb/dev-storage.c     |  2 +-
 hw/usb/host-legacy.c     |  2 +-
 hw/virtio/virtio-bus.c   |  4 +---
 hw/xen/xen_platform.c    |  2 +-
 include/hw/qdev-core.h   |  1 -
 qdev-monitor.c           |  2 +-
 15 files changed, 21 insertions(+), 29 deletions(-)

diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index b46bd5e..7f5ab24 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -326,7 +326,7 @@ static void acpi_piix_eject_slot(PIIX4PMState *s, unsigned slots)
             if (pc->no_hotplug) {
                 slot_free = false;
             } else {
-                qdev_free(qdev);
+                object_unparent(OBJECT(qdev));
             }
         }
     }
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 533f6dd..e374a93 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -164,7 +164,7 @@ int qdev_init(DeviceState *dev)
     if (local_err != NULL) {
         qerror_report_err(local_err);
         error_free(local_err);
-        qdev_free(dev);
+        object_unparent(OBJECT(dev));
         return -1;
     }
     return 0;
@@ -258,7 +258,7 @@ void qbus_reset_all_fn(void *opaque)
 int qdev_simple_unplug_cb(DeviceState *dev)
 {
     /* just zap it */
-    qdev_free(dev);
+    object_unparent(OBJECT(dev));
     return 0;
 }
 
@@ -280,12 +280,6 @@ void qdev_init_nofail(DeviceState *dev)
     }
 }
 
-/* Unlink device from bus and free the structure.  */
-void qdev_free(DeviceState *dev)
-{
-    object_unparent(OBJECT(dev));
-}
-
 void qdev_machine_creation_done(void)
 {
     /*
@@ -458,7 +452,7 @@ static void bus_unparent(Object *obj)
 
     while ((kid = QTAILQ_FIRST(&bus->children)) != NULL) {
         DeviceState *dev = kid->child;
-        qdev_free(dev);
+        object_unparent(OBJECT(dev));
     }
     if (bus->parent) {
         QLIST_REMOVE(bus, sibling);
diff --git a/hw/pci/pci-hotplug-old.c b/hw/pci/pci-hotplug-old.c
index 619fe47..8dbc3c1 100644
--- a/hw/pci/pci-hotplug-old.c
+++ b/hw/pci/pci-hotplug-old.c
@@ -248,7 +248,7 @@ static PCIDevice *qemu_pci_hot_add_storage(Monitor *mon,
         }
         dev = pci_create(bus, devfn, "virtio-blk-pci");
         if (qdev_prop_set_drive(&dev->qdev, "drive", dinfo->bdrv) < 0) {
-            qdev_free(&dev->qdev);
+            object_unparent(OBJECT(dev));
             dev = NULL;
             break;
         }
diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
index e6b22b8..290abab 100644
--- a/hw/pci/pci_bridge.c
+++ b/hw/pci/pci_bridge.c
@@ -391,7 +391,7 @@ void pci_bridge_exitfn(PCIDevice *pci_dev)
     pci_bridge_region_cleanup(s, s->windows);
     memory_region_destroy(&s->address_space_mem);
     memory_region_destroy(&s->address_space_io);
-    /* qbus_free() is called automatically by qdev_free() */
+    /* qbus_free() is called automatically during device deletion */
 }
 
 /*
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 50af3c1..a27acf3 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -251,7 +251,7 @@ static int pcie_cap_slot_hotplug(DeviceState *qdev,
                                    PCI_EXP_SLTSTA_PDS);
         pcie_cap_slot_event(d, PCI_EXP_HP_EV_PDC);
     } else {
-        qdev_free(&pci_dev->qdev);
+        object_unparent(OBJECT(pci_dev));
         pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTSTA,
                                      PCI_EXP_SLTSTA_PDS);
         pcie_cap_slot_event(d, PCI_EXP_HP_EV_PDC);
diff --git a/hw/pci/shpc.c b/hw/pci/shpc.c
index eb092fd..29a8c36 100644
--- a/hw/pci/shpc.c
+++ b/hw/pci/shpc.c
@@ -254,7 +254,7 @@ static void shpc_free_devices_in_slot(SHPCDevice *shpc, int slot)
          ++devfn) {
         PCIDevice *affected_dev = shpc->sec_bus->devices[devfn];
         if (affected_dev) {
-            qdev_free(&affected_dev->qdev);
+            object_unparent(OBJECT(affected_dev));
         }
     }
 }
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index cd67db5..f93a81c 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -1239,7 +1239,7 @@ static int virtio_ccw_busdev_unplug(DeviceState *dev)
 
     css_generate_sch_crws(sch->cssid, sch->ssid, sch->schid, 1, 0);
 
-    qdev_free(dev);
+    object_unparent(OBJECT(dev));
     return 0;
 }
 
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 24ec52f..ea916d1 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -178,7 +178,7 @@ static int scsi_qdev_init(DeviceState *qdev)
         d = scsi_device_find(bus, dev->channel, dev->id, dev->lun);
         assert(d);
         if (d->lun == dev->lun && dev != d) {
-            qdev_free(&d->qdev);
+            object_unparent(OBJECT(d));
         }
     }
 
@@ -231,13 +231,13 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockDriverState *bdrv,
     }
     if (qdev_prop_set_drive(dev, "drive", bdrv) < 0) {
         error_setg(errp, "Setting drive property failed");
-        qdev_free(dev);
+        object_unparent(OBJECT(dev));
         return NULL;
     }
     object_property_set_bool(OBJECT(dev), true, "realized", &err);
     if (err != NULL) {
         error_propagate(errp, err);
-        qdev_free(dev);
+        object_unparent(OBJECT(dev));
         return NULL;
     }
     return SCSI_DEVICE(dev);
diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index 72d5b92..ca329be 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -356,8 +356,9 @@ void usb_port_location(USBPort *downstream, USBPort *upstream, int portnr)
 
 void usb_unregister_port(USBBus *bus, USBPort *port)
 {
-    if (port->dev)
-        qdev_free(&port->dev->qdev);
+    if (port->dev) {
+        object_unparent(OBJECT(port->dev));
+    }
     QTAILQ_REMOVE(&bus->free, port, next);
     bus->nfree--;
 }
@@ -505,7 +506,7 @@ int usb_device_delete_addr(int busnr, int addr)
         return -1;
     dev = port->dev;
 
-    qdev_free(&dev->qdev);
+    object_unparent(OBJECT(dev));
     return 0;
 }
 
diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index 1d81ac2..c434c56 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -703,7 +703,7 @@ static USBDevice *usb_msd_init(USBBus *bus, const char *filename)
         return NULL;
     }
     if (qdev_prop_set_drive(&dev->qdev, "drive", dinfo->bdrv) < 0) {
-        qdev_free(&dev->qdev);
+        object_unparent(OBJECT(dev));
         return NULL;
     }
     if (qdev_init(&dev->qdev) < 0)
diff --git a/hw/usb/host-legacy.c b/hw/usb/host-legacy.c
index 3a5f705..3cc9c42 100644
--- a/hw/usb/host-legacy.c
+++ b/hw/usb/host-legacy.c
@@ -132,7 +132,7 @@ USBDevice *usb_host_device_open(USBBus *bus, const char *devname)
     return dev;
 
 fail:
-    qdev_free(&dev->qdev);
+    object_unparent(OBJECT(dev));
     return NULL;
 }
 
diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index 6849a01..e6b103c 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -67,7 +67,6 @@ void virtio_bus_reset(VirtioBusState *bus)
 /* Destroy the VirtIODevice */
 void virtio_bus_destroy_device(VirtioBusState *bus)
 {
-    DeviceState *qdev;
     BusState *qbus = BUS(bus);
     VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
     DPRINTF("%s: remove device.\n", qbus->name);
@@ -76,8 +75,7 @@ void virtio_bus_destroy_device(VirtioBusState *bus)
         if (klass->device_unplug != NULL) {
             klass->device_unplug(qbus->parent);
         }
-        qdev = DEVICE(bus->vdev);
-        qdev_free(qdev);
+        object_unparent(OBJECT(bus->vdev));
         bus->vdev = NULL;
     }
 }
diff --git a/hw/xen/xen_platform.c b/hw/xen/xen_platform.c
index 79bf0b3..70875e4 100644
--- a/hw/xen/xen_platform.c
+++ b/hw/xen/xen_platform.c
@@ -95,7 +95,7 @@ static void unplug_nic(PCIBus *b, PCIDevice *d, void *o)
     if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
             PCI_CLASS_NETWORK_ETHERNET
             && strcmp(d->name, "xen-pci-passthrough") != 0) {
-        qdev_free(DEVICE(d));
+        object_unparent(OBJECT(d));
     }
 }
 
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index e191ca0..f2043a6 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -221,7 +221,6 @@ void qdev_init_nofail(DeviceState *dev);
 void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                  int required_for_version);
 void qdev_unplug(DeviceState *dev, Error **errp);
-void qdev_free(DeviceState *dev);
 int qdev_simple_unplug_cb(DeviceState *dev);
 void qdev_machine_creation_done(void);
 bool qdev_machine_modified(void);
diff --git a/qdev-monitor.c b/qdev-monitor.c
index 0cb53a5..4f558c4 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -520,7 +520,7 @@ DeviceState *qdev_device_add(QemuOpts *opts)
         qdev->id = id;
     }
     if (qemu_opt_foreach(opts, set_property, qdev, 1) != 0) {
-        qdev_free(qdev);
+        object_unparent(OBJECT(qdev));
         object_unref(OBJECT(qdev));
         return NULL;
     }
-- 
1.8.3.1