ACPI / scan: Start matching drivers after trying scan handlers

ACPI scan handlers should always be attached to struct acpi_device
objects before any ACPI drivers, but there is a window during which
a driver may be attached to a struct acpi_device before checking if
there is a matching scan handler.  Namely, that will happen if an
ACPI driver module is loaded during acpi_bus_scan() right after
the first namespace walk is complete and before the given device
is processed by the second namespace walk.

To prevent that from happening, set the match_driver flags of
struct acpi_device objects right before running device_attach()
for them in acpi_bus_device_attach().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index fbdb82e..4d377a22 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1677,7 +1677,6 @@ void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
 
 void acpi_device_add_finalize(struct acpi_device *device)
 {
-	device->flags.match_driver = true;
 	dev_set_uevent_suppress(&device->dev, false);
 	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
 }
@@ -1916,8 +1915,12 @@ static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,
 		return AE_OK;
 
 	ret = acpi_scan_attach_handler(device);
-	if (ret)
-		return ret > 0 ? AE_OK : AE_CTRL_DEPTH;
+	if (ret < 0)
+		return AE_CTRL_DEPTH;
+
+	device->flags.match_driver = true;
+	if (ret > 0)
+		return AE_OK;
 
 	ret = device_attach(&device->dev);
 	return ret >= 0 ? AE_OK : AE_CTRL_DEPTH;