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Commit 3d255699 authored by Viresh Kumar's avatar Viresh Kumar
Browse files

OPP: Protect dev_list with opp_table lock 



The dev_list needs to be protected with a lock, else we may have
simultaneous access (addition/removal) to it and that would be racy.
Extend scope of the opp_table lock to protect dev_list as well.

Tested-by: default avatarNiklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
parent 404b1369

drivers/opp/core.c

+19 −2
Original line number Diff line number Diff line
@@ -48,9 +48,14 @@ static struct opp_device *_find_opp_dev(const struct device *dev, 
static struct opp_table *_find_opp_table_unlocked(struct device *dev)

{

	struct opp_table *opp_table;

	bool found;



	list_for_each_entry(opp_table, &opp_tables, node) {

		if (_find_opp_dev(dev, opp_table)) {

		mutex_lock(&opp_table->lock);

		found = !!_find_opp_dev(dev, opp_table);

		mutex_unlock(&opp_table->lock);



		if (found) {

			_get_opp_table_kref(opp_table);



			return opp_table;
@@ -766,6 +771,8 @@ struct opp_device *_add_opp_dev(const struct device *dev, 


	/* Initialize opp-dev */

	opp_dev->dev = dev;



	mutex_lock(&opp_table->lock);

	list_add(&opp_dev->node, &opp_table->dev_list);



	/* Create debugfs entries for the opp_table */
@@ -773,6 +780,7 @@ struct opp_device *_add_opp_dev(const struct device *dev, 
	if (ret)

		dev_err(dev, "%s: Failed to register opp debugfs (%d)\n",

			__func__, ret);

	mutex_unlock(&opp_table->lock);



	return opp_dev;

}
@@ -791,6 +799,7 @@ static struct opp_table *_allocate_opp_table(struct device *dev) 
	if (!opp_table)

		return NULL;



	mutex_init(&opp_table->lock);

	INIT_LIST_HEAD(&opp_table->dev_list);



	opp_dev = _add_opp_dev(dev, opp_table);
@@ -812,7 +821,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev) 


	BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head);

	INIT_LIST_HEAD(&opp_table->opp_list);

	mutex_init(&opp_table->lock);

	kref_init(&opp_table->kref);



	/* Secure the device table modification */
@@ -854,6 +862,10 @@ static void _opp_table_kref_release(struct kref *kref) 
	if (!IS_ERR(opp_table->clk))

		clk_put(opp_table->clk);



	/*

	 * No need to take opp_table->lock here as we are guaranteed that no

	 * references to the OPP table are taken at this point.

	 */

	opp_dev = list_first_entry(&opp_table->dev_list, struct opp_device,

				   node);
@@ -1716,6 +1728,9 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev, 
{

	struct dev_pm_opp *opp, *tmp;



	/* Protect dev_list */

	mutex_lock(&opp_table->lock);



	/* Find if opp_table manages a single device */

	if (list_is_singular(&opp_table->dev_list)) {

		/* Free static OPPs */
@@ -1733,6 +1748,8 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev, 
	} else {

		_remove_opp_dev(_find_opp_dev(dev, opp_table), opp_table);

	}



	mutex_unlock(&opp_table->lock);

}



void _dev_pm_opp_find_and_remove_table(struct device *dev, bool remove_all)

drivers/opp/cpu.c

+2 −0
Original line number Diff line number Diff line
@@ -226,8 +226,10 @@ int dev_pm_opp_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 
	cpumask_clear(cpumask);



	if (opp_table->shared_opp == OPP_TABLE_ACCESS_SHARED) {

		mutex_lock(&opp_table->lock);

		list_for_each_entry(opp_dev, &opp_table->dev_list, node)

			cpumask_set_cpu(opp_dev->dev->id, cpumask);

		mutex_unlock(&opp_table->lock);

	} else {

		cpumask_set_cpu(cpu_dev->id, cpumask);

	}

drivers/opp/opp.h

+1 −1
Original line number Diff line number Diff line
@@ -126,7 +126,7 @@ enum opp_table_access { 
 * @dev_list:	list of devices that share these OPPs

 * @opp_list:	table of opps

 * @kref:	for reference count of the table.

 * @lock:	mutex protecting the opp_list.

 * @lock:	mutex protecting the opp_list and dev_list.

 * @np:		struct device_node pointer for opp's DT node.

 * @clock_latency_ns_max: Max clock latency in nanoseconds.

 * @shared_opp: OPP is shared between multiple devices.