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>

1 files changed, 12 insertions, 22 deletions

diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
index 09a84402986d..fbc63d5e459f 100644
--- 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;
 }