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Commit b4718c02 authored by Dmitry Torokhov's avatar Dmitry Torokhov Committed by Rafael J. Wysocki
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PM / OPP: take RCU lock in dev_pm_opp_get_opp_count 



A lot of callers are missing the fact that dev_pm_opp_get_opp_count
needs to be called under RCU lock. Given that RCU locks can safely be
nested, instead of providing *_locked() API, let's take RCU lock inside
dev_pm_opp_get_opp_count() and leave callers as is.

Signed-off-by: default avatarDmitry Torokhov <dtor@chromium.org>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 0fe30da2

drivers/base/power/opp.c

+8 −7
Original line number Diff line number Diff line
@@ -216,9 +216,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq); 
 * This function returns the number of available opps if there are any,

 * else returns 0 if none or the corresponding error value.

 *

 * Locking: This function must be called under rcu_read_lock(). This function

 * internally references two RCU protected structures: device_opp and opp which

 * are safe as long as we are under a common RCU locked section.

 * Locking: This function takes rcu_read_lock().

 */

int dev_pm_opp_get_opp_count(struct device *dev)

{
@@ -226,13 +224,14 @@ int dev_pm_opp_get_opp_count(struct device *dev) 
	struct dev_pm_opp *temp_opp;

	int count = 0;



	opp_rcu_lockdep_assert();

	rcu_read_lock();



	dev_opp = find_device_opp(dev);

	if (IS_ERR(dev_opp)) {

		int r = PTR_ERR(dev_opp);

		dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);

		return r;

		count = PTR_ERR(dev_opp);

		dev_err(dev, "%s: device OPP not found (%d)\n",

			__func__, count);

		goto out_unlock;

	}



	list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
@@ -240,6 +239,8 @@ int dev_pm_opp_get_opp_count(struct device *dev) 
			count++;

	}



out_unlock:

	rcu_read_unlock();

	return count;

}

EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);