[PATCH 4/8] PCI hotplug: fix wrong assumption in acpi_get_hp_hw_control_from_firmware

Kenji Kaneshige
2009-01-28T11:55:49Z

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>

---
drivers/pci/hotplug/acpi_pcihp.c | 34 ++++++++++++----------------------
1 file changed, 12 insertions(+), 22 deletions(-)

Index: linux-2.6.29-rc2/drivers/pci/hotplug/acpi_pcihp.c
===================================================================
--- linux-2.6.29-rc2.orig/drivers/pci/hotplug/acpi_pcihp.c
+++ linux-2.6.29-rc2/drivers/pci/hotplug/acpi_pcihp.c
@@ -373,12 +373,10 @@ EXPORT_SYMBOL_GPL(acpi_get_hp_params_fro
*
* 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 |
@@ -410,26 +408,18 @@ int acpi_get_hp_hw_control_from_firmware
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) {
@@ -448,13 +438,13 @@ int acpi_get_hp_hw_control_from_firmware
}

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;
}