[PATCH 3.16 145/370] PM / devfreq: Add proper locking around list_del()

[Ben Hutchings]

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Axel Lin <axel.lin@xxxxxxxxxx>

commit 0f376c9cd86c23f37312d37748b233660ef9d9af upstream.

Use devfreq_list_lock around list_del() to prevent list corruption.

Signed-off-by: Axel Lin <axel.lin@xxxxxxxxxx>
Acked-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/devfreq/devfreq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -507,17 +507,19 @@ struct devfreq *devfreq_add_device(struc
 	if (devfreq->governor)
 		err = devfreq->governor->event_handler(devfreq,
 					DEVFREQ_GOV_START, NULL);
-	mutex_unlock(&devfreq_list_lock);
 	if (err) {
 		dev_err(dev, "%s: Unable to start governor for the device\n",
 			__func__);
 		goto err_init;
 	}
+	mutex_unlock(&devfreq_list_lock);
 
 	return devfreq;
 
 err_init:
 	list_del(&devfreq->node);
+	mutex_unlock(&devfreq_list_lock);
+
 	device_unregister(&devfreq->dev);
 err_dev:
 	kfree(devfreq);