From dca026139317dcbc642a30320d551f559692182f Mon Sep 17 00:00:00 2001 From: =?utf8?q?Lothar=20Wa=C3=9Fmann?= Date: Thu, 29 May 2008 17:54:52 +0200 Subject: [PATCH] [CPUFREQ] fix double unlock of cpu_policy_rwsem in drivers/cpufreq/cpufreq.c MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Dave Jones --- drivers/cpufreq/cpufreq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 7fce038fa57..86f0a243062 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/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"); -- 2.20.1