ACPI / scan: Do not try to attach scan handlers to devices having them

In acpi_bus_device_attach(), if there is an ACPI device object
for the given handle and that device object has a scan handler
attached to it already, there's nothing more to do for that handle.
Moreover, if acpi_scan_attach_handler() is called then, it may
execute the .attach() callback of the ACPI scan handler already
attached to the device object and that may lead to interesting
breakage.

For this reason, make acpi_bus_device_attach() return success
immediately when the handle's device object has a scan handler
attached to it.

Reported-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Cc: 3.10+ <stable@vger.kernel.org>

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 10985573aaa7c680613c1412c958d81d7af22f64..080d75962c5723da2ea9b9bcafbe850b5ccf171d 100644 (file)
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1981,6 +1981,9 @@ static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,
        if (acpi_bus_get_device(handle, &device))
                return AE_CTRL_DEPTH;
 
+       if (device->handler)
+               return AE_OK;
+
        ret = acpi_scan_attach_handler(device);
        if (ret)
                return ret > 0 ? AE_OK : AE_CTRL_DEPTH;