From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752368Ab1DYUPw (ORCPT ); Mon, 25 Apr 2011 16:15:52 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:48876 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751095Ab1DYUPv (ORCPT ); Mon, 25 Apr 2011 16:15:51 -0400 From: "Rafael J. Wysocki" To: Linux PM mailing list Subject: [PATCH] ACPI / PM: Avoid infinite recurrence while registering power resources Date: Mon, 25 Apr 2011 22:15:58 +0200 User-Agent: KMail/1.13.6 (Linux/2.6.39-rc4+; KDE/4.6.0; x86_64; ; ) Cc: Len Brown , LKML , ACPI Devel Mailing List , Pascal Dormeau MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201104252215.58860.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki There is at least one BIOS with a DSDT containing a power resource object with a _PR0 entry pointing back to that power resource. In consequence, while registering that power resource acpi_bus_get_power_flags() sees that it depends on itself and tries to register it again, which leads to an infinitely deep recurrence. This problem was introduced by commit bf325f9538d8c89312be305b9779e (ACPI / PM: Register power resource devices as soon as they are needed). To fix this problem use the observation that power resources cannot be power manageable and prevent acpi_bus_get_power_flags() from being called for power resource objects. References: https://bugzilla.kernel.org/show_bug.cgi?id=31872 Reported-and-tested-by: Pascal Dormeau Signed-off-by: Rafael J. Wysocki --- drivers/acpi/scan.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux-2.6/drivers/acpi/scan.c =================================================================== --- linux-2.6.orig/drivers/acpi/scan.c +++ linux-2.6/drivers/acpi/scan.c @@ -943,6 +943,10 @@ static int acpi_bus_get_flags(struct acp if (ACPI_SUCCESS(status)) device->flags.lockable = 1; + /* Power resources cannot be power manageable. */ + if (device->device_type == ACPI_BUS_TYPE_POWER) + return 0; + /* Presence of _PS0|_PR0 indicates 'power manageable' */ status = acpi_get_handle(device->handle, "_PS0", &temp); if (ACPI_FAILURE(status))