[PATCH] ACPI / video: Do not bind to device objects with a driver or scan handler

["Rafael J. Wysocki" <rjw@sisk.pl>]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

With the introduction of ACPI scan handlers, ACPI device objects
with an ACPI scan handler attached to them must not be bound to
an ACPI driver any more.  Unfortunately, however, the ACPI video
driver attempts to do just that if there is a _ROM ACPI control
method defined under a device object with an ACPI scan handler.

Prevent that from happening by making the video driver's "add"
routine check if the device object already has a driver or
ACPI scan handler attached to it and return an error code in
that case.  That is not sufficient, though, because
acpi_bus_driver_init() would then clear the device object's
driver_data that may be set by the scan handler attached to it,
so for the fix to work acpi_bus_driver_init() has to be modified
to leave driver_data as is on errors.

References: https://bugzilla.kernel.org/show_bug.cgi?id=58091
Reported-and-bisected-by: Dmitry S. Demin <dmitryy.demin@gmail.com>
Reported-and-tested-by: Jason Cassell <bluesloth600@gmail.com>
Tracked-down-by: Aaron Lu <aaron.lu@intel.com>
Cc: 3.9+ <stable@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/scan.c  |    5 +----
 drivers/acpi/video.c |    3 +++
 2 files changed, 4 insertions(+), 4 deletions(-)

Index: linux-pm/drivers/acpi/video.c
===================================================================
--- linux-pm.orig/drivers/acpi/video.c
+++ linux-pm/drivers/acpi/video.c
@@ -1722,6 +1722,9 @@ static int acpi_video_bus_add(struct acp
 	int error;
 	acpi_status status;
 
+	if (device->handler || device->driver)
+		return -EINVAL;
+
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
 				device->parent->handle, 1,
 				acpi_video_bus_match, NULL,
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -1133,11 +1133,8 @@ acpi_bus_driver_init(struct acpi_device
 		return -ENOSYS;
 
 	result = driver->ops.add(device);
-	if (result) {
-		device->driver = NULL;
-		device->driver_data = NULL;
+	if (result)
 		return result;
-	}
 
 	device->driver = driver;