From patchwork Wed Sep 3 13:04:28 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Kosina X-Patchwork-Id: 4834311 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 00A62C0338 for ; Wed, 3 Sep 2014 13:04:46 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5BC30200E1 for ; Wed, 3 Sep 2014 13:04:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A450D2021A for ; Wed, 3 Sep 2014 13:04:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932546AbaICNEd (ORCPT ); Wed, 3 Sep 2014 09:04:33 -0400 Received: from cantor2.suse.de ([195.135.220.15]:34903 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932379AbaICNEc (ORCPT ); Wed, 3 Sep 2014 09:04:32 -0400 Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id DBCBBACA4; Wed, 3 Sep 2014 13:04:29 +0000 (UTC) Date: Wed, 3 Sep 2014 15:04:28 +0200 (CEST) From: Jiri Kosina To: "Gautham R. Shenoy" , "Rafael J. Wysocki" , Oleg Nesterov , "Srivatsa S. Bhat" , Ingo Molnar cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: [PATCH] ACPI / cpuidle: fix deadlock between cpuidle_lock and cpu_hotplug.lock In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-8.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There is a following AB-BA dependency between cpu_hotplug.lock and cpuidle_lock: 1) cpu_hotplug.lock -> cpuidle_lock enable_nonboot_cpus() _cpu_up() cpu_hotplug_being() LOCK(cpu_hotplug.lock) cpu_notify() ... acpi_processor_hotplug() cpuidle_pause_and_lock() LOCK(cpuidle_lock) 2) cpuidle_lock -> cpu_hotplug.lock acpi_os_execute_deferred() workqueue ... acpi_processor_cst_has_changed() cpuidle_pause_and_lock() LOCK(cpuidle_lock) get_online_cpus() LOCK(cpu_hotplug.lock) Fix this by reversing the order acpi_processor_cst_has_changed() does thigs -- let it first execute the protection against CPU hotplug by calling get_online_cpus() and obtain the cpuidle lock only after that (and perform the symmentric change when allowing CPUs hotplug again and dropping cpuidle lock). Spotted by lockdep. Signed-off-by: Jiri Kosina Reviewed-by: Gautham R. Shenoy --- drivers/acpi/processor_idle.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 3dca36d..17f9ec5 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1071,9 +1071,9 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr) if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) { - cpuidle_pause_and_lock(); /* Protect against cpu-hotplug */ get_online_cpus(); + cpuidle_pause_and_lock(); /* Disable all cpuidle devices */ for_each_online_cpu(cpu) { @@ -1100,8 +1100,8 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr) cpuidle_enable_device(dev); } } - put_online_cpus(); cpuidle_resume_and_unlock(); + put_online_cpus(); } return 0;