Commit 3f4a782b authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Dave Jones
Browse files

[CPUFREQ] fix (utter) cpufreq_add_dev mess 



OK, I've tried to clean it up the best I could, but please test this with
concurrent cpu hotplug and cpufreq add/remove in loops. I'm sure we will make
other interesting findings.

This is step one of fixing the overall locking dependency mess in cpufreq.

Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
CC: rjw@sisk.pl
CC: mingo@elte.hu
CC: Shaohua Li <shaohua.li@intel.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Dave Young <hidave.darkstar@gmail.com>
CC: "Rafael J. Wysocki" <rjw@sisk.pl>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: sven.wegener@stealer.net
CC: cpufreq@vger.kernel.org
CC: Thomas Renninger <trenn@suse.de>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
parent ee88415c

drivers/cpufreq/cpufreq.c

+40 −25
Original line number Diff line number Diff line
@@ -761,6 +761,10 @@ static struct kobj_type ktype_cpufreq = { 
 * cpufreq_add_dev - add a CPU device

 *

 * Adds the cpufreq interface for a CPU device.

 *

 * The Oracle says: try running cpufreq registration/unregistration concurrently

 * with with cpu hotplugging and all hell will break loose. Tried to clean this

 * mess up, but more thorough testing is needed. - Mathieu

 */

static int cpufreq_add_dev(struct sys_device *sys_dev)

{
@@ -804,15 +808,12 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) 
		goto nomem_out;

	}

	if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL)) {

		kfree(policy);

		ret = -ENOMEM;

		goto nomem_out;

		goto err_free_policy;

	}

	if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL)) {

		free_cpumask_var(policy->cpus);

		kfree(policy);

		ret = -ENOMEM;

		goto nomem_out;

		goto err_free_cpumask;

	}



	policy->cpu = cpu;
@@ -820,7 +821,8 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) 


	/* Initially set CPU itself as the policy_cpu */

	per_cpu(policy_cpu, cpu) = cpu;

	lock_policy_rwsem_write(cpu);

	ret = (lock_policy_rwsem_write(cpu) < 0);

	WARN_ON(ret);



	init_completion(&policy->kobj_unregister);

	INIT_WORK(&policy->update, handle_update);
@@ -833,7 +835,7 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) 
	ret = cpufreq_driver->init(policy);

	if (ret) {

		dprintk("initialization failed\n");

		goto err_out;

		goto err_unlock_policy;

	}

	policy->user_policy.min = policy->min;

	policy->user_policy.max = policy->max;
@@ -858,15 +860,21 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) 
		/* Check for existing affected CPUs.

		 * They may not be aware of it due to CPU Hotplug.

		 */

		managed_policy = cpufreq_cpu_get(j);		/* FIXME: Where is this released?  What about error paths? */

		managed_policy = cpufreq_cpu_get(j);

		if (unlikely(managed_policy)) {



			/* Set proper policy_cpu */

			unlock_policy_rwsem_write(cpu);

			per_cpu(policy_cpu, cpu) = managed_policy->cpu;



			if (lock_policy_rwsem_write(cpu) < 0)

				goto err_out_driver_exit;

			if (lock_policy_rwsem_write(cpu) < 0) {

				/* Should not go through policy unlock path */

				if (cpufreq_driver->exit)

					cpufreq_driver->exit(policy);

				ret = -EBUSY;

				cpufreq_cpu_put(managed_policy);

				goto err_free_cpumask;

			}



			spin_lock_irqsave(&cpufreq_driver_lock, flags);

			cpumask_copy(managed_policy->cpus, policy->cpus);
@@ -877,12 +885,14 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) 
			ret = sysfs_create_link(&sys_dev->kobj,

						&managed_policy->kobj,

						"cpufreq");

			if (ret)

				goto err_out_driver_exit;



			cpufreq_debug_enable_ratelimit();

			ret = 0;

			goto err_out_driver_exit; /* call driver->exit() */

			if (!ret)

				cpufreq_cpu_put(managed_policy);

			/*

			 * Success. We only needed to be added to the mask.

			 * Call driver->exit() because only the cpu parent of

			 * the kobj needed to call init().

			 */

			goto out_driver_exit; /* call driver->exit() */

		}

	}

#endif
@@ -892,25 +902,25 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) 
	ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq, &sys_dev->kobj,

				   "cpufreq");

	if (ret)

		goto err_out_driver_exit;

		goto out_driver_exit;



	/* 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_driver_exit;

			goto err_out_kobj_put;

		drv_attr++;

	}

	if (cpufreq_driver->get) {

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

		if (ret)

			goto err_out_driver_exit;

			goto err_out_kobj_put;

	}

	if (cpufreq_driver->target) {

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

		if (ret)

			goto err_out_driver_exit;

			goto err_out_kobj_put;

	}



	spin_lock_irqsave(&cpufreq_driver_lock, flags);
@@ -928,13 +938,15 @@ static int cpufreq_add_dev(struct sys_device *sys_dev) 
			continue;



		dprintk("CPU %u already managed, adding link\n", j);

		cpufreq_cpu_get(cpu);

		managed_policy = cpufreq_cpu_get(cpu);

		cpu_sys_dev = get_cpu_sysdev(j);

		ret = sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,

					"cpufreq");

		if (ret)

		if (ret) {

			cpufreq_cpu_put(managed_policy);

			goto err_out_unregister;

		}

	}



	policy->governor = NULL; /* to assure that the starting sequence is

				  * run in cpufreq_set_policy */
@@ -965,17 +977,20 @@ err_out_unregister: 
		per_cpu(cpufreq_cpu_data, j) = NULL;

	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);



err_out_kobj_put:

	kobject_put(&policy->kobj);

	wait_for_completion(&policy->kobj_unregister);



err_out_driver_exit:

out_driver_exit:

	if (cpufreq_driver->exit)

		cpufreq_driver->exit(policy);



err_out:

err_unlock_policy:

	unlock_policy_rwsem_write(cpu);

err_free_cpumask:

	free_cpumask_var(policy->cpus);

err_free_policy:

	kfree(policy);



nomem_out:

	module_put(cpufreq_driver->owner);

module_out:

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