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: [<c01b4564>] 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: [<c018fd18>] sysdev_driver_register+0x74/0x130 stack backtrace: [<c002f588>] (dump_stack+0x0/0x14) from [<c00692fc>] (print_unlock_inbalance_bug+0xc8/0x104) [<c0069234>] (print_unlock_inbalance_bug+0x0/0x104) from [<c006b7ac>] (lock_release_non_nested+0xc4/0x19c) r6:00000028 r5:c3c1ab80 r4:c01b4564 [<c006b6e8>] (lock_release_non_nested+0x0/0x19c) from [<c006b9e0>] (lock_release+0x15c/0x18c) r8:60000013 r7:00000001 r6:c01b4564 r5:c0541bb4 r4:c3c1ab80 [<c006b884>] (lock_release+0x0/0x18c) from [<c0061ba0>] (up_write+0x24/0x30) r8:c0541b80 r7:00000000 r6:ffffffea r5:c3c34828 r4:c0541b8c [<c0061b7c>] (up_write+0x0/0x30) from [<c01b4564>] (unlock_policy_rwsem_write+0x30/0x40) r4:c3c34884 [<c01b4534>] (unlock_policy_rwsem_write+0x0/0x40) from [<c01b4c40>] (cpufreq_add_dev+0x324/0x398) [<c01b491c>] (cpufreq_add_dev+0x0/0x398) from [<c018fd64>] (sysdev_driver_register+0xc0/0x130) [<c018fca4>] (sysdev_driver_register+0x0/0x130) from [<c01b3574>] (cpufreq_register_driver+0xbc/0x174) Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de> Signed-off-by: Dave Jones <davej@redhat.com> |
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.. | ||
Kconfig | ||
Makefile | ||
cpufreq.c | ||
cpufreq_conservative.c | ||
cpufreq_ondemand.c | ||
cpufreq_performance.c | ||
cpufreq_powersave.c | ||
cpufreq_stats.c | ||
cpufreq_userspace.c | ||
freq_table.c |