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Commit a532c015 authored by Saravana Kannan's avatar Saravana Kannan Committed by Junjie Wu
Browse files

cpufreq: Fix race between policy initialization and cpufreq_cpu_get() 



When the first CPU in a policy comes online or is brought up for the first
time, a policy is allocated for it. However, the kobject corresponding to
it is not allocated until later. So, if cpufreq_cpu_get() is called in
this interval, it would try to "get" an uninitialized kobject. Avoid this
by allocating the kobject at the same time as allocating the policy.

Change-Id: I676408da41e3feccb85b74e2a4a23f3a1f6892bd
Signed-off-by: default avatarSaravana Kannan <skannan@codeaurora.org>
parent 718b9859

drivers/cpufreq/cpufreq.c

+16 −24
Original line number Diff line number Diff line
@@ -932,45 +932,32 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy, 
	struct freq_attr **drv_attr;

	int ret = 0;



	/* prepare interface data */

	ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,

				   &dev->kobj, "cpufreq");

	if (ret)

		return ret;



	/* set up files for this cpu device */

	drv_attr = cpufreq_driver->attr;

	while ((drv_attr) && (*drv_attr)) {

		ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));

		if (ret)

			goto err_out_kobj_put;

			return ret;

		drv_attr++;

	}

	if (cpufreq_driver->get) {

		ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);

		if (ret)

			goto err_out_kobj_put;

			return ret;

	}



	ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);

	if (ret)

		goto err_out_kobj_put;

		return ret;



	if (cpufreq_driver->bios_limit) {

		ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);

		if (ret)

			goto err_out_kobj_put;

			return ret;

	}



	ret = cpufreq_add_dev_symlink(policy);

	if (ret)

		goto err_out_kobj_put;



	return ret;



err_out_kobj_put:

	kobject_put(&policy->kobj);

	wait_for_completion(&policy->kobj_unregister);

	return ret;

}
@@ -1075,7 +1062,7 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu) 
	return policy;

}



static struct cpufreq_policy *cpufreq_policy_alloc(void)

static struct cpufreq_policy *cpufreq_policy_alloc(struct device *dev)

{

	struct cpufreq_policy *policy;
@@ -1089,6 +1076,11 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void) 
	if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))

		goto err_free_cpumask;



	/* prepare interface data */

	if (kobject_init_and_add(&policy->kobj, &ktype_cpufreq,

				   &dev->kobj, "cpufreq"))

		goto err_free_rcpumask;



	INIT_LIST_HEAD(&policy->policy_list);

	init_rwsem(&policy->rwsem);

	spin_lock_init(&policy->transition_lock);
@@ -1096,6 +1088,8 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void) 


	return policy;



err_free_rcpumask:

	free_cpumask_var(policy->related_cpus);

err_free_cpumask:

	free_cpumask_var(policy->cpus);

err_free_policy:
@@ -1213,7 +1207,7 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) 
	policy = recover_policy ? cpufreq_policy_restore(cpu) : NULL;

	if (!policy) {

		recover_policy = false;

		policy = cpufreq_policy_alloc();

		policy = cpufreq_policy_alloc(dev);

		if (!policy)

			goto nomem_out;

	}
@@ -1353,11 +1347,9 @@ err_get_freq: 
	if (cpufreq_driver->exit)

		cpufreq_driver->exit(policy);

err_set_policy_cpu:

	if (recover_policy) {

	/* Do not leave stale fallback data behind. */

	per_cpu(cpufreq_cpu_data_fallback, cpu) = NULL;

	cpufreq_policy_put_kobj(policy);

	}

	cpufreq_policy_free(policy);



nomem_out: