[Qemu-devel] [PATCH 9/9] hotplug: refactor hotplug to leverage new QOM functions

[Anthony Liguori <aliguori@us.ibm.com>]

1) DeviceState::unplug requests for an eject to happen
   - the default implementation is a forced eject

2) A bus can eject a device by setting the parent_bus to NULL
   - this detaches the device from the bus
   - this does *not* cause the device to disappear

3) The current implementation on unplug also registers an eject notifier
   - the eject notifier will detach the device the parent.  This will cause the
     device to disappear

4) A purely guest initiated unplug will not delete a device but will cause the
   device to appear detached from the guests PoV.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
 hw/acpi_piix4.c   |    3 ++-
 hw/pci.c          |   10 +++++++++-
 hw/pcie.c         |    2 +-
 hw/qdev.c         |   22 ++++++++++++++++++++++
 hw/qdev.h         |    2 ++
 hw/shpc.c         |    2 +-
 hw/xen_platform.c |    2 +-
 7 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/hw/acpi_piix4.c b/hw/acpi_piix4.c
index 72d6e5c..eac53b3 100644
--- a/hw/acpi_piix4.c
+++ b/hw/acpi_piix4.c
@@ -305,7 +305,8 @@ static void acpi_piix_eject_slot(PIIX4PMState *s, unsigned slots)
             if (pc->no_hotplug) {
                 slot_free = false;
             } else {
-                qdev_free(qdev);
+                /* Force eject of device */
+                qdev_set_parent_bus(qdev, NULL);
             }
         }
     }
diff --git a/hw/pci.c b/hw/pci.c
index 437af70..cc555c2 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -46,6 +46,14 @@ static char *pcibus_get_dev_path(DeviceState *dev);
 static char *pcibus_get_fw_dev_path(DeviceState *dev);
 static int pcibus_reset(BusState *qbus);
 
+static void pcibus_remove_child(BusState *bus, DeviceState *dev)
+{
+    PCIDevice *pci_dev = PCI_DEVICE(dev);
+    PCIBus *pci_bus = PCI_BUS(bus);
+
+    pci_bus->devices[pci_dev->devfn] = NULL;
+}
+
 static Property pci_props[] = {
     DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
     DEFINE_PROP_STRING("romfile", PCIDevice, romfile),
@@ -65,6 +73,7 @@ static void pci_bus_class_init(ObjectClass *klass, void *data)
     k->get_dev_path = pcibus_get_dev_path;
     k->get_fw_dev_path = pcibus_get_fw_dev_path;
     k->reset = pcibus_reset;
+    k->remove_child = pcibus_remove_child;
 }
 
 static const TypeInfo pci_bus_info = {
@@ -833,7 +842,6 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
 static void do_pci_unregister_device(PCIDevice *pci_dev)
 {
     qemu_free_irqs(pci_dev->irq);
-    pci_dev->bus->devices[pci_dev->devfn] = NULL;
     pci_config_free(pci_dev);
 }
 
diff --git a/hw/pcie.c b/hw/pcie.c
index 7c92f19..d10ffea 100644
--- a/hw/pcie.c
+++ b/hw/pcie.c
@@ -235,7 +235,7 @@ 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);
+        qdev_set_parent_bus(DEVICE(pci_dev), NULL);
         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/qdev.c b/hw/qdev.c
index 525a0cb..be41f00 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -62,6 +62,7 @@ static void qdev_property_add_legacy(DeviceState *dev, Property *prop,
 
 static void bus_remove_child(BusState *bus, DeviceState *child)
 {
+    BusClass *bc = BUS_GET_CLASS(bus);
     BusChild *kid;
 
     QTAILQ_FOREACH(kid, &bus->children, sibling) {
@@ -71,6 +72,11 @@ static void bus_remove_child(BusState *bus, DeviceState *child)
             snprintf(name, sizeof(name), "child[%d]", kid->index);
             QTAILQ_REMOVE(&bus->children, kid, sibling);
             object_property_del(OBJECT(bus), name, NULL);
+
+            if (bc->remove_child) {
+                bc->remove_child(bus, kid->child);
+            }
+
             g_free(kid);
             return;
         }
@@ -192,9 +198,20 @@ void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
     dev->alias_required_for_version = required_for_version;
 }
 
+static void qdev_finish_unplug(Notifier *notifier, void *data)
+{
+    DeviceState *dev = DEVICE(data);
+
+    /* unparent the object -- this should release the last reference to the
+       child*/
+    object_unparent(OBJECT(dev));
+    g_free(notifier);
+}
+
 void qdev_unplug(DeviceState *dev, Error **errp)
 {
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
+    Notifier *notifier;
 
     if (!dev->parent_bus->allow_hotplug) {
         error_set(errp, QERR_BUS_NO_HOTPLUG, dev->parent_bus->name);
@@ -204,6 +221,11 @@ void qdev_unplug(DeviceState *dev, Error **errp)
 
     qdev_hot_removed = true;
 
+    notifier = g_malloc0(sizeof(*notifier));
+    notifier->notify = qdev_finish_unplug;
+
+    notifier_list_add(&dev->eject_notifier, notifier);
+
     if (dc->unplug(dev) < 0) {
         error_set(errp, QERR_UNDEFINED_ERROR);
         return;
diff --git a/hw/qdev.h b/hw/qdev.h
index 5009072..7ae8d5d 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -99,6 +99,8 @@ struct BusClass {
      */
     char *(*get_fw_dev_path)(DeviceState *dev);
     int (*reset)(BusState *bus);
+
+    void (*remove_child)(BusState *bus, DeviceState *dev);
 };
 
 typedef struct BusChild {
diff --git a/hw/shpc.c b/hw/shpc.c
index a5baf24..ce507e7 100644
--- a/hw/shpc.c
+++ b/hw/shpc.c
@@ -253,7 +253,7 @@ 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);
+            qdev_set_parent_bus(DEVICE(affected_dev), NULL);
         }
     }
 }
diff --git a/hw/xen_platform.c b/hw/xen_platform.c
index 0d6c2ff..5c5ecf8 100644
--- a/hw/xen_platform.c
+++ b/hw/xen_platform.c
@@ -87,7 +87,7 @@ static void unplug_nic(PCIBus *b, PCIDevice *d, void *o)
 {
     if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
             PCI_CLASS_NETWORK_ETHERNET) {
-        qdev_free(&d->qdev);
+        qdev_set_parent_bus(dev, NULL);
     }
 }
 
-- 
1.7.5.4