ACPI: PAD: xen: Check ACPI_COMPANION() against NULL

Every platform driver can be forced to match a device that doesn't match
its list of device IDs because of device_match_driver_override(), so
platform drivers that rely on the existence of a device's ACPI companion
object need to verify its presence.

Accordingly, add a requisite ACPI_COMPANION() check against NULL to the
Xen variant of the ACPI processor aggregator device (PAD) driver.

Fixes: 112b2f978afe ("ACPI: PAD: xen: Convert to a platform driver")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Juergen Gross <jgross@suse.com>
Link: https://patch.msgid.link/3427762.aeNJFYEL58@rafael.j.wysocki

diff --git a/drivers/xen/xen-acpi-pad.c b/drivers/xen/xen-acpi-pad.c
index 75a39862c1df3ea5bd73a70cfbe7f55446601398..5b98e0e9380768375229710b96f51293f0807603 100644 (file)
--- a/drivers/xen/xen-acpi-pad.c
+++ b/drivers/xen/xen-acpi-pad.c
@@ -110,9 +110,13 @@ static void acpi_pad_notify(acpi_handle handle, u32 event,
 
 static int acpi_pad_probe(struct platform_device *pdev)
 {
-       struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+       struct acpi_device *device;
        acpi_status status;
 
+       device = ACPI_COMPANION(&pdev->dev);
+       if (!device)
+               return -ENODEV;
+
        strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
        strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);