From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752641AbYE2J4N (ORCPT ); Thu, 29 May 2008 05:56:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750825AbYE2J4B (ORCPT ); Thu, 29 May 2008 05:56:01 -0400 Received: from mail.karo-electronics.de ([213.146.116.110]:41723 "EHLO mail.karo-electronics.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750780AbYE2Jzx (ORCPT ); Thu, 29 May 2008 05:55:53 -0400 Message-ID: <18494.32161.453409.293610@ipc1.ka-ro> Date: Thu, 29 May 2008 11:55:45 +0200 X-Mailer: VM 7.19 under Emacs 21.4.1 From: =?iso-8859-15?q?Lothar_Wa=DFmann?= To: Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Subject: [PATCH] cpufreq: fix double unlock of cpu_policy_rwsem in drivers/cpufreq/cpufreq.c Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In drivers/cpufreq/cpufreq.c the function cpufreq_add_dev() takes the error exit 'err_out_unregister' from different places once with the 'cpu_policy_rwsem' lock held, once with the lock released: | if (ret) | goto err_out_unregister; | } | | policy->governor = NULL; /* to assure that the starting sequence is | * run in cpufreq_set_policy */ | | /* set default policy */ | ret = __cpufreq_set_policy(policy, &new_policy); | policy->user_policy.policy = policy->policy; | policy->user_policy.governor = policy->governor; | | unlock_policy_rwsem_write(cpu); | | if (ret) { | dprintk("setting policy failed\n"); | goto err_out_unregister; | } This leads to the following error message in case of a failing __cpufreq_set_policy() call: ===================================== [ BUG: bad unlock balance detected! ] ------------------------------------- swapper/1 is trying to release lock (&per_cpu(cpu_policy_rwsem, cpu)) at: [] unlock_policy_rwsem_write+0x30/0x40 but there are no more locks to release! other info that might help us debug this: 1 lock held by swapper/1: #0: (sysdev_drivers_lock){--..}, at: [] sysdev_driver_register+0x74/0x130 stack backtrace: [] (dump_stack+0x0/0x14) from [] (print_unlock_inbalance_bug+0xc8/0x104) [] (print_unlock_inbalance_bug+0x0/0x104) from [] (lock_release_non_nested+0xc4/0x19c) r6:00000028 r5:c3c1ab80 r4:c01b4564 [] (lock_release_non_nested+0x0/0x19c) from [] (lock_release+0x15c/0x18c) r8:60000013 r7:00000001 r6:c01b4564 r5:c0541bb4 r4:c3c1ab80 [] (lock_release+0x0/0x18c) from [] (up_write+0x24/0x30) r8:c0541b80 r7:00000000 r6:ffffffea r5:c3c34828 r4:c0541b8c [] (up_write+0x0/0x30) from [] (unlock_policy_rwsem_write+0x30/0x40) r4:c3c34884 [] (unlock_policy_rwsem_write+0x0/0x40) from [] (cpufreq_add_dev+0x324/0x398) [] (cpufreq_add_dev+0x0/0x398) from [] (sysdev_driver_register+0xc0/0x130) [] (sysdev_driver_register+0x0/0x130) from [] (cpufreq_register_driver+0xbc/0x174) Signed-off-by: Lothar Waßmann --- --- linux-2.6.26-rc3/drivers/cpufreq/cpufreq.c +++ linux-2.6.26-rc3-karo/drivers/cpufreq/cpufreq.c @@ -928,13 +928,13 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) policy->user_policy.policy = policy->policy; policy->user_policy.governor = policy->governor; - unlock_policy_rwsem_write(cpu); - if (ret) { dprintk("setting policy failed\n"); goto err_out_unregister; } + unlock_policy_rwsem_write(cpu); + kobject_uevent(&policy->kobj, KOBJ_ADD); module_put(cpufreq_driver->owner); dprintk("initialization complete\n"); -- Lothar Waßmann ___________________________________________________________ Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10 Geschäftsführer: Matthias Kaussen Handelsregistereintrag: Amtsgericht Aachen, HRB 4996 www.karo-electronics.de | info@karo-electronics.de ___________________________________________________________