ACPI: sysfs: Prefer "compatible" modalias

BugLink: https://bugs.launchpad.net/bugs/1916056

commit 36af2d5 upstream.

Commit 8765c5b ("ACPI / scan: Rework modalias creation when
"compatible" is present") may create two "MODALIAS=" in one uevent
file if specific conditions are met.

This breaks systemd-udevd, which assumes each "key" in one uevent file
to be unique. The internal implementation of systemd-udevd overwrites
the first MODALIAS with the second one, so its kmod rule doesn't load
the driver for the first MODALIAS.

So if both the ACPI modalias and the OF modalias are present, use the
latter to ensure that there will be only one MODALIAS.

Link: systemd/systemd#18163
Suggested-by: Mika Westerberg <[email protected]>
Fixes: 8765c5b ("ACPI / scan: Rework modalias creation when "compatible" is present")
Signed-off-by: Kai-Heng Feng <[email protected]>
Reviewed-by: Mika Westerberg <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Cc: 4.1+ <[email protected]> # 4.1+
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Kamal Mostafa <[email protected]>
Signed-off-by: Stefan Bader <[email protected]>

Author: khfeng

drivers/acpi/device_sysfs.c

@@ -251,20 +251,12 @@ int __acpi_device_uevent_modalias(struct acpi_device *adev,
 	if (add_uevent_var(env, "MODALIAS="))
 		return -ENOMEM;
 
-	len = create_pnp_modalias(adev, &env->buf[env->buflen - 1],
-				  sizeof(env->buf) - env->buflen);
-	if (len < 0)
-		return len;
-
-	env->buflen += len;
-	if (!adev->data.of_compatible)
-		return 0;
-
-	if (len > 0 && add_uevent_var(env, "MODALIAS="))
-		return -ENOMEM;
-
-	len = create_of_modalias(adev, &env->buf[env->buflen - 1],
-				 sizeof(env->buf) - env->buflen);
+	if (adev->data.of_compatible)
+		len = create_of_modalias(adev, &env->buf[env->buflen - 1],
+					 sizeof(env->buf) - env->buflen);
+	else
+		len = create_pnp_modalias(adev, &env->buf[env->buflen - 1],
+					  sizeof(env->buf) - env->buflen);
 	if (len < 0)
 		return len;