PCI hotplug: fix wrong assumption in acpi_get_hp_hw_control_from_firmware

Current acpi_get_hp_hw_control_from_firmware() has a assumption that
pci_bus->self is NULL on a PCI root bus. But it might not be true on
some platforms. Because of this wrong assumption, current
acpi_get_hp_hw_control_from_firmware() might cause endless loop. We
must check pci_bus->parent instead.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
index 09a8440..fbc63d5 100644 (file)
--- a/drivers/pci/hotplug/acpi_pcihp.c
+++ b/drivers/pci/hotplug/acpi_pcihp.c
@@ -372,12 +372,10 @@ EXPORT_SYMBOL_GPL(acpi_get_hp_params_from_firmware);
  *
  * Attempt to take hotplug control from firmware.
  */
-int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags)
+int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev, u32 flags)
 {
        acpi_status status;
        acpi_handle chandle, handle;
-       struct pci_dev *pdev = dev;
-       struct pci_bus *parent;
        struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
 
        flags &= (OSC_PCI_EXPRESS_NATIVE_HP_CONTROL |
@@ -409,26 +407,18 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags)
                string = (struct acpi_buffer){ ACPI_ALLOCATE_BUFFER, NULL };
        }
 
-       pdev = dev;
-       handle = DEVICE_ACPI_HANDLE(&dev->dev);
-       while (!handle) {
+       handle = DEVICE_ACPI_HANDLE(&pdev->dev);
+       if (!handle) {
                /*
                 * This hotplug controller was not listed in the ACPI name
                 * space at all. Try to get acpi handle of parent pci bus.
                 */
-               if (!pdev || !pdev->bus->parent)
-                       break;
-               parent = pdev->bus->parent;
-               dbg("Could not find %s in acpi namespace, trying parent\n",
-                   pci_name(pdev));
-               if (!parent->self)
-                       /* Parent must be a host bridge */
-                       handle = acpi_get_pci_rootbridge_handle(
-                                       pci_domain_nr(parent),
-                                       parent->number);
-               else
-                       handle = DEVICE_ACPI_HANDLE(&(parent->self->dev));
-               pdev = parent->self;
+               struct pci_bus *pbus;
+               for (pbus = pdev->bus; pbus; pbus = pbus->parent) {
+                       handle = acpi_pci_get_bridge_handle(pbus);
+                       if (handle)
+                               break;
+               }
        }
 
        while (handle) {
@@ -447,13 +437,13 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags)
        }
 
        dbg("Cannot get control of hotplug hardware for pci %s\n",
-           pci_name(dev));
+           pci_name(pdev));
 
        kfree(string.pointer);
        return -ENODEV;
 got_one:
-       dbg("Gained control for hotplug HW for pci %s (%s)\n", pci_name(dev),
-                       (char *)string.pointer);
+       dbg("Gained control for hotplug HW for pci %s (%s)\n",
+           pci_name(pdev), (char *)string.pointer);
        kfree(string.pointer);
        return 0;
 }