From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965018AbbA1Fc6 (ORCPT ); Wed, 28 Jan 2015 00:32:58 -0500 Received: from mail.kernel.org ([198.145.29.136]:36758 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760436AbbA1ENv (ORCPT ); Tue, 27 Jan 2015 23:13:51 -0500 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jiri Kosina , "Rafael J. Wysocki" , Zefan Li Subject: [PATCH 3.4 07/91] ACPI / cpuidle: fix deadlock between cpuidle_lock and cpu_hotplug.lock Date: Wed, 28 Jan 2015 12:06:20 +0800 Message-Id: <1422418236-12852-13-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1422418050-12581-1-git-send-email-lizf@kernel.org> References: <1422418050-12581-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jiri Kosina 3.4.105-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 6726655dfdd2dc60c035c690d9f10cb69d7ea075 upstream. 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_begin() 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 Signed-off-by: Rafael J. Wysocki Signed-off-by: Zefan Li --- 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 6cba428..e1180ce 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1195,9 +1195,9 @@ 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) { @@ -1222,8 +1222,8 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr) cpuidle_enable_device(&_pr->power.dev); } } - put_online_cpus(); cpuidle_resume_and_unlock(); + put_online_cpus(); } return 0; -- 1.9.1