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[CPUFREQ] fix a lockdep warning

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There is no need to do sysfs_remove_link() or kobject_put() etc.
when policy_rwsem_write is held, move them after releasing the lock.

This fixes the lockdep warning:

halt/4071 is trying to acquire lock:
 (s_active){++++.+}, at: [<c0000000001ef868>] .sysfs_addrm_finish+0x58/0xc0

but task is already holding lock:
 (&per_cpu(cpu_policy_rwsem, cpu)){+.+.+.}, at: [<c0000000004cd6ac>] .lock_policy_rwsem_write+0x84/0xf4

Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Amerigo Wang 2010-03-04 03:23:46 -05:00 committed by Dave Jones
parent 2eaa9cfdf3
commit 499bca9b6d
1 changed files with 14 additions and 5 deletions
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19
drivers/cpufreq/cpufreq.c
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@ -1113,6 +1113,8 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
unsigned int cpu = sys_dev->id;
unsigned long flags;
struct cpufreq_policy *data;
struct kobject *kobj;
struct completion *cmp;
#ifdef CONFIG_SMP
struct sys_device *cpu_sys_dev;
unsigned int j;
@ -1141,10 +1143,11 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
dprintk("removing link\n");
cpumask_clear_cpu(cpu, data->cpus);
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
sysfs_remove_link(&sys_dev->kobj, "cpufreq");
kobj = &sys_dev->kobj;
cpufreq_cpu_put(data);
cpufreq_debug_enable_ratelimit();
unlock_policy_rwsem_write(cpu);
sysfs_remove_link(kobj, "cpufreq");
return 0;
}
#endif
@ -1181,7 +1184,10 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
data->governor->name, CPUFREQ_NAME_LEN);
#endif
cpu_sys_dev = get_cpu_sysdev(j);
sysfs_remove_link(&cpu_sys_dev->kobj, "cpufreq");
kobj = &cpu_sys_dev->kobj;
unlock_policy_rwsem_write(cpu);
sysfs_remove_link(kobj, "cpufreq");
lock_policy_rwsem_write(cpu);
cpufreq_cpu_put(data);
}
}
@ -1192,19 +1198,22 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
kobject_put(&data->kobj);
kobj = &data->kobj;
cmp = &data->kobj_unregister;
unlock_policy_rwsem_write(cpu);
kobject_put(kobj);
/* we need to make sure that the underlying kobj is actually
* not referenced anymore by anybody before we proceed with
* unloading.
*/
dprintk("waiting for dropping of refcount\n");
wait_for_completion(&data->kobj_unregister);
wait_for_completion(cmp);
dprintk("wait complete\n");
lock_policy_rwsem_write(cpu);
if (cpufreq_driver->exit)
cpufreq_driver->exit(data);
unlock_policy_rwsem_write(cpu);
free_cpumask_var(data->related_cpus);