ACPI / hotplug / PCI: Simplify disable_slot()

After recent PCI core changes related to the rescan/remove locking,
the ACPIPHP's disable_slot() function is only called under the
general PCI rescan/remove lock, so it doesn't have to use
dev_in_slot() any more to avoid race conditions.  Make it simply
walk the devices on the bus and drop the ones in the slot being
disabled and drop dev_in_slot() which has no more users.

Moreover, to avoid problems described in the changelog of commit
29ed1f29b68a (PCI: pciehp: Fix null pointer deref when hot-removing
SR-IOV device), make disable_slot() carry out the list walk in
reverse order.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index e2a783fdb98fdc6be6cb24f52a9a828ba48f2ba6..f24c19c8f8c4685c63b91743eca3bffc60a6b432 100644 (file)
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -625,32 +625,15 @@ static void __ref enable_slot(struct acpiphp_slot *slot)
        }
 }
 
-/* return first device in slot, acquiring a reference on it */
-static struct pci_dev *dev_in_slot(struct acpiphp_slot *slot)
-{
-       struct pci_bus *bus = slot->bus;
-       struct pci_dev *dev;
-       struct pci_dev *ret = NULL;
-
-       down_read(&pci_bus_sem);
-       list_for_each_entry(dev, &bus->devices, bus_list)
-               if (PCI_SLOT(dev->devfn) == slot->device) {
-                       ret = pci_dev_get(dev);
-                       break;
-               }
-       up_read(&pci_bus_sem);
-
-       return ret;
-}
-
 /**
  * disable_slot - disable a slot
  * @slot: ACPI PHP slot
  */
 static void disable_slot(struct acpiphp_slot *slot)
 {
+       struct pci_bus *bus = slot->bus;
+       struct pci_dev *dev, *prev;
        struct acpiphp_func *func;
-       struct pci_dev *pdev;
 
        /*
         * enable_slot() enumerates all functions in this device via
@@ -658,10 +641,9 @@ static void disable_slot(struct acpiphp_slot *slot)
         * methods (_EJ0, etc.) or not.  Therefore, we remove all functions
         * here.
         */
-       while ((pdev = dev_in_slot(slot))) {
-               pci_stop_and_remove_bus_device(pdev);
-               pci_dev_put(pdev);
-       }
+       list_for_each_entry_safe_reverse(dev, prev, &bus->devices, bus_list)
+               if (PCI_SLOT(dev->devfn) == slot->device)
+                       pci_stop_and_remove_bus_device(dev);
 
        list_for_each_entry(func, &slot->funcs, sibling)
                acpiphp_bus_trim(func_to_handle(func));