From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751999AbaBHPH7 (ORCPT ); Sat, 8 Feb 2014 10:07:59 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:63288 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751833AbaBHPHz (ORCPT ); Sat, 8 Feb 2014 10:07:55 -0500 From: "Rafael J. Wysocki" To: ACPI Devel Maling List Cc: Linux PCI , Linux Kernel Mailing List Subject: [PATCH] ACPI / hotplug / PCI: Execute _EJ0 under the ACPI scan lock Date: Sat, 08 Feb 2014 16:22:30 +0100 Message-ID: <1629492.WLGZp2sePX@vostro.rjw.lan> User-Agent: KMail/4.11.4 (Linux/3.13.0+; KDE/4.11.4; x86_64; ; ) MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki Since acpi_device_hotplug() assumes that ACPI handles of device objects passed to it will not become invalid while acpi_scan_lock is being held, make acpiphp_disable_slot() acquire acpi_scan_lock, because it generally causes _EJ0 to be executed for one of the devices in the slot and that may cause its ACPI handle to become invalid. Signed-off-by: Rafael J. Wysocki --- Hi All, This change is not necessary in 3.14-rc (it wouldn't hurt, though), but it closes a (mostly theoretical) race on top of the changes I've queued up for 3.15 in linux-next. Thanks, Rafael --- drivers/pci/hotplug/acpiphp_glue.c | 6 ++++++ 1 file changed, 6 insertions(+) Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c =================================================================== --- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c +++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c @@ -1007,9 +1007,15 @@ int acpiphp_disable_slot(struct acpiphp_ { int ret; + /* + * Acquire acpi_scan_lock to ensure that the execution of _EJ0 in + * acpiphp_disable_and_eject_slot() will be synchronized properly. + */ + acpi_scan_lock_acquire(); pci_lock_rescan_remove(); ret = acpiphp_disable_and_eject_slot(slot); pci_unlock_rescan_remove(); + acpi_scan_lock_release(); return ret; }