ACPI / PCI: Use global PCI rescan-remove locking in PCI root hotplug

Multiple race conditions are possible between the addition and removal of
PCI devices during ACPI PCI host bridge hotplug and the generic PCI bus
rescan and device removal that can be triggered via sysfs.

To avoid those race conditions make the ACPI PCI host bridge addition and
removal code use global PCI rescan-remove locking.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/acpi/pci_root.c

@@ -596,7 +596,9 @@ static int acpi_pci_root_add(struct acpi_device *device,
 		pci_assign_unassigned_root_bus_resources(root->bus);
 	}
 
+	pci_lock_rescan_remove();
 	pci_bus_add_devices(root->bus);
+	pci_unlock_rescan_remove();
 	return 1;
 
 end:
@@ -608,13 +610,17 @@ static void acpi_pci_root_remove(struct acpi_device *device)
 {
 	struct acpi_pci_root *root = acpi_driver_data(device);
 
+	pci_lock_rescan_remove();
+
 	pci_stop_root_bus(root->bus);
 
 	device_set_run_wake(root->bus->bridge, false);
 	pci_acpi_remove_bus_pm_notifier(device);
 
 	pci_remove_root_bus(root->bus);
 
+	pci_unlock_rescan_remove();
+
 	kfree(root);
 }